Sequential separation and purification method of single rare earth elements europium and gadolinium based on ion exchange

Abstract

The present invention discloses a sequential separation and purification method of single rare earth elements europium and gadolinium based on ion exchange, which belongs to the technical field of ion exchange method. The method comprises sequentially treating a sample pretreatment liquid dissolved in hydrochloric acid with a first exchange column filled with AG 50W-X12 resin, replacing the hydrochloric acid system and treating a second exchange column filled with TODGA resin, wherein the second exchange column treatment comprises eluting with 27mL of hydrochloric acid with a concentration of 1.1mol / L, then eluting with 11mL of hydrochloric acid with a concentration of 1.1mol / L to obtain europium, and then eluting with 12mL of hydrochloric acid with a concentration of 1.1mol / L to obtain gadolinium; the present invention can fully separate europium and gadolinium from its rare earth elements and between europium and gadolinium from rare earth ores to obtain single elements europium and gadolinium with high purity, and at the same time, it can use the same concentration of hydrochloric acid multiple times, and the process is simple and easy to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of ion exchange method, in particular to the technical field of separating rare earth elements europium and gadolinium by ion exchange method. Background Art

[0002] High-purity single rare earth elements europium (Eu) and gadolinium (Gd) are widely used in high-tech industries and military fields due to their unique optical, electrical and magnetic properties, such as precision instruments, communication equipment, medical imaging technology, and national defense science and technology. The commonly used separation and purification method is ion exchange, and the treatment process usually includes: injecting a sample solution containing rare earth elements into a columnar container filled with ion exchange resin, relying on the ability of ion exchange resin to selectively adsorb specific ions, and using a series of eluents with different chemical properties, gradually eluting through the exchange column to obtain separated rare earth elements. The eluent used is generally an acidic or alkaline solution. The movement rate of the rare earth ions can be adjusted according to the difference in the stability of the compounds formed between the rare earth ions and the resin. Since the stabilities of the compounds formed by different rare earth ions and the resin are different, the rates at which they move to the column outlet during the elution process will also be different. Heavier rare earth ions or those more firmly bound to the resin will pass through the exchange column more slowly. Therefore, as the elution process proceeds, different rare earth ions will be eluted out of the exchange column at different time points, thereby achieving the purpose of collecting different rare earth elements in chronological order and achieving the effect of separating and purifying rare earth elements.

[0003] However, due to the similar physical and chemical properties of different rare earth elements, it is difficult to separate and extract these rare earth elements individually, especially heavy rare earth elements such as europium and gadolinium. The existing technology cannot completely separate them from each other through ion exchange to obtain high-purity europium and gadolinium without adjacent rare earth element impurities. Summary of the invention

[0004] In order to solve the problems of the prior art, the purpose of the present invention is to provide a new method for sequential separation and purification of single rare earth elements europium and gadolinium based on ion exchange, which can sequentially separate single rare earth elements europium and gadolinium from rare earth ores to obtain completely separated high-purity europium and gadolinium that do not contain adjacent rare earth element impurities.

[0005] The technical solution of the present invention is as follows:

[0006] A method for sequentially separating and purifying single rare earth elements europium and gadolinium based on ion exchange, comprising:

[0007] (1) dissolving the digested rare earth ore sample in 2.5 mol / L hydrochloric acid to obtain a sample pretreatment solution;

[0008] (2) adding the sample pretreatment solution to a first exchange column that has been pre-cleaned and equilibrated with 4 mL of 2.5 mol / L hydrochloric acid, eluting with 20 mL of 2.5 mol / L hydrochloric acid, and then eluting with 25 mL of 6 mol / L nitric acid solution and collecting the corresponding eluate to obtain an eluate containing rare earth and barium;

[0009] (3) evaporating the rare earth and barium-containing eluate to dryness, then adding concentrated hydrochloric acid to simmer, repeating the evaporation and concentrated hydrochloric acid simmering process several times until the rare earth and barium-containing eluate becomes a hydrochloric acid system, and then dissolving it in 0.2 mL of a 1.1 mol / L hydrochloric acid solution to obtain a treated dispersion;

[0010] (4) adding the treated dispersion to a second exchange column that was pre-cleaned and equilibrated with 4 mL of 1.1 mol / L hydrochloric acid, eluting with 27 mL of 1.1 mol / L hydrochloric acid, then eluting with 11 mL of 1.1 mol / L hydrochloric acid and collecting the corresponding eluate to obtain a single rare earth element europium, then eluting with 12 mL of 1.1 mol / L hydrochloric acid and collecting the corresponding eluate to obtain a single rare earth element gadolinium;

[0011] The first exchange column is an ion exchange column filled with 2 mL of AG 50W-X12 resin, and the second exchange column is an ion exchange column filled with 2.5 mL of TODGA resin.

[0012] According to some specific embodiments of the present invention, the digested rare earth ore sample is obtained by a hydrofluoric acid-nitric acid closed pressure acid dissolution method.

[0013] According to some specific embodiments of the present invention, the pre-cleaning in step (2) includes: pre-cleaning the first exchange column with 30 mL of 6 mol / L nitric acid solution, 5 mL of pure water and 30 mL of 6 mol / L hydrochloric acid.

[0014] According to some specific embodiments of the present invention, the pre-cleaning in step (4) includes: pre-cleaning the second exchange column with 5 mL of pure water and 20 mL of a 0.02 mol / L hydrochloric acid solution.

[0015] The present invention has the following beneficial effects:

[0016] The present invention can fully remove major elements such as Al, Fe, Ti, Mg, K and Rb in a rare earth ore sample through a first exchange column, wash out barium (Ba) and all rare earth elements, then remove barium and light rare earth elements (La-Sm) through a second exchange column, and sequentially obtain single elements europium and gadolinium. In this process, not only can europium and gadolinium be fully separated from other rare earth elements such as samarium, so that other rare earth elements such as samarium can be fully recovered, but europium and gadolinium can also be completely separated from each other to obtain high-purity single element europium or gadolinium.

[0017] The present invention can achieve sufficient separation of the difficult-to-separate rare earth elements europium and gadolinium by simply eluting two exchange columns with acid and repeatedly using hydrochloric acid of the same concentration. The treatment process is simple, the operation is convenient, and the separation and purification efficiency is high.

[0018] The present invention can fully separate and purify europium and gadolinium from their adjacent rare earth elements and from each other in rare earth ores, and the separation and purification rate can reach 99%, and the recovery rate can approach or reach 99%; BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of an exchange column device used for separating and purifying europium and gadolinium elements in an embodiment of the present invention.

[0020] Figure 2 This is a diagram showing the effect of separation and purification of europium and gadolinium elements in Example 1 of the present invention.

[0021] Figure 3 This is a diagram showing the effect of separation and purification of europium and gadolinium elements in Example 2 of the present invention. DETAILED DESCRIPTION

[0022] The technical scheme of the present invention will be further described below in conjunction with the embodiments and drawings of the present invention. The embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] See attached Figure 1 The separation and purification device used in the following examples includes a first exchange column 1 filled with AG 50W-X12 resin and eluted with A1 acid, and a second exchange column 2 filled with TODGA resin and eluted with A2 acid, wherein the first exchange column 1 has a length of 9 cm, a diameter of 0.7 cm, a capacity of 4 mL, and is filled with 2 mL of AG 50W-X12 resin, and the second exchange column 2 is a quartz column with a length of 22 cm, a diameter of 0.4 cm, a capacity of 14 mL, and is filled with 2.5 mL of TODGA resin.

[0024] The AG50W-X12 mentioned above is a cation exchange resin produced by Bio-Rad Corporation of the United States, and the resin particle size is 200-400 mesh; the TODGA resin is produced by Eichrom Corporation of the United States, the type is Normal, contains N,N,N',N'-tetraoctyldiglycolamide extractant, and the particle size is 50-100 μm.

[0025] The following embodiment provides a method for simultaneously separating and purifying single rare earth elements europium and gadolinium by the above separation and purification device, including:

[0026] (1) dissolving the digested rare earth ore sample in 2.5 mol / L hydrochloric acid to obtain a sample pretreatment solution;

[0027] (2) adding the sample pretreatment solution to the first exchange column after pre-cleaning and equilibration, and eluting with 20 mL of 2.5 mol / L hydrochloric acid to remove major elements such as Al, Fe, Ti, Mg, K and Rb, and then eluting with 25 mL of 6 mol / L nitric acid solution to wash out barium (Ba) and all rare earth elements in the sample to obtain an eluent containing rare earth and barium;

[0028] (3) The rare earth and barium-containing eluate is evaporated to dryness, and then concentrated hydrochloric acid is added and simmered for about 30 minutes, and evaporated to dryness again to convert the eluate into a hydrochloric acid system, and then the eluate is dissolved in 0.2 mL of a 1.1 mol / L hydrochloric acid solution to obtain a treated dispersion;

[0029] (4) Add the treated dispersion to the second exchange column that has been pre-cleaned and balanced, and use 27 mL of 1.1 mol / L hydrochloric acid for elution to remove barium and light rare earth elements (La-Sm), then use 11 mL of 1.1 mol / L hydrochloric acid for elution, and collect the corresponding eluate to obtain a single rare earth element europium, and then use 12 mL of 1.1 mol / L hydrochloric acid for elution, and collect the corresponding eluate to obtain a single rare earth element gadolinium.

[0030] The hydrofluoric acid-nitric acid closed pressure acid dissolution method used in the following examples includes: adding a mixed solution of concentrated hydrofluoric acid and nitric acid in a volume ratio of 3:1 to the sample, then heating on a hot plate at 120° C. for 5 days, and then repeatedly digesting with aqua regia until the obtained sample solution becomes clear and transparent.

[0031] Example 1

[0032] The separation and purification of single elements of europium and gadolinium is carried out through the following process:

[0033] (1) pre-cleaning the first exchange column with 30 mL of 6 mol / L nitric acid solution, 5 mL of Milli-Q water and 30 mL of 6 mol / L hydrochloric acid, and then balancing the first exchange column with 4 mL of 2.5 mol / L hydrochloric acid solution; pre-cleaning the second exchange column with 5 mL of Milli-Q water and 20 mL of 0.02 mol / L hydrochloric acid solution, and then balancing the pre-cleaned second exchange column with 4 mL of 1.1 mol / L hydrochloric acid solution;

[0034] (2) A basalt geological standard substance BHVO-2 sample is digested by a hydrofluoric acid-nitric acid closed pressure acid dissolution method until the obtained sample solution becomes clear and transparent, and then the digested sample is dissolved in a hydrochloric acid solution with a volume of 0.5 mL and a concentration of 2.5 mol / L to obtain a sample pretreatment solution, which is loaded onto the first exchange column after equilibrium; wherein the standard substance used is a basalt rock standard substance, which can be used to evaluate the effect of the present invention on conventional geological samples;

[0035] (3) According to (2) to (4) in the specific implementation method, single rare earth elements europium and gadolinium are obtained.

[0036] The separation and purification effect of this embodiment is shown in the attached Figure 2 As shown, it can be seen that the present invention can completely separate europium and gadolinium from other rare earth elements such as Sm, and can completely separate europium and gadolinium from each other to obtain single europium or gadolinium element with high purity.

[0037] Example 2

[0038] The separation and purification of single elements of europium and gadolinium is carried out through the following process:

[0039] (1) pre-cleaning the first exchange column with 30 mL of 6 mol / L nitric acid solution, 5 mL of Milli-Q water and 30 mL of 6 mol / L hydrochloric acid, and then balancing the pre-cleaned first exchange column with 4 mL of 2.5 mol / L hydrochloric acid; pre-cleaning the second exchange column with 5 mL of Milli-Q water and 20 mL of 0.02 mol / L hydrochloric acid solution, and then balancing the pre-cleaned second exchange column with 4 mL of 1.1 mol / L hydrochloric acid solution;

[0040] (2) The national first-level standard material GBW07161 rare earth ore sample is digested by a hydrofluoric acid-nitric acid closed pressure acid dissolution method until the obtained sample solution becomes clear and transparent, and then the digested sample is dissolved in 0.5 mL of a 2.5 mol / L hydrochloric acid solution to obtain a sample pretreatment solution, which is loaded onto the first exchange column after equilibrium; wherein the standard material GBW07161 used is taken from the Zudong rare earth mining area in Longnan County, Jiangxi Province, and is a typical ion adsorption type medium-heavy rare earth ore, which can be used to evaluate the effect of the present invention on rare earth ore geological samples;

[0041] (3) According to (2) to (4) in the specific implementation method, single rare earth elements europium and gadolinium are obtained.

[0042] The separation and purification effect of this embodiment is shown in the attached Figure 3 As shown, it can be seen from the separation that the present invention can completely separate europium and gadolinium from other rare earth elements such as Sm, and can completely separate europium and gadolinium from each other to obtain single europium or gadolinium element with high purity.

[0043] During the above process, Figure 3 1 mL of the eluate before and after the peaks of europium and gadolinium in the graph shown was collected in a 5 mL centrifuge tube, and the rare earth element content was tested by inductively coupled plasma mass spectrometry (ICP-MS), and the measured rare earth element content was compared with the pure rare earth element content of the sample to calculate the recovery rate. The results show that the separation and purification rates of europium and gadolinium in this embodiment can reach 99%, and the recovery rate can approach or reach 99%.

[0044] It should be noted that the above is only a preferred embodiment of the present invention, which should not limit the protection scope of the technical solution of the present invention. Any modification of the technical solution recorded in the above embodiments and equivalent replacement of technical features by ordinary technicians in the field within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for sequential separation and purification of single rare earth elements europium and gadolinium based on ion exchange, characterized in that: It includes: (1) dissolving the digested rare earth ore sample in 2.5 mol / L hydrochloric acid to obtain a sample pretreatment solution; (2) adding the sample pretreatment solution to a first exchange column that has been pre-cleaned and equilibrated with 4 mL of 2.5 mol / L hydrochloric acid, eluting with 20 mL of 2.5 mol / L hydrochloric acid, and then eluting with 25 mL of 6 mol / L nitric acid solution and collecting the corresponding eluate to obtain an eluate containing rare earth and barium; (3) evaporating the rare earth and barium-containing eluate to dryness, then adding concentrated hydrochloric acid to simmer, repeating the evaporation and concentrated hydrochloric acid simmering process several times until the rare earth and barium-containing eluate becomes a hydrochloric acid system, and then dissolving it in 0.2 mL of a 1.1 mol / L hydrochloric acid solution to obtain a treated dispersion; (4) adding the treated dispersion to a second exchange column that has been pre-cleaned and equilibrated with 4 mL of 1.1 mol / L hydrochloric acid, eluting with 27 mL of 1.1 mol / L hydrochloric acid, then eluting with 11 mL of 1.1 mol / L hydrochloric acid and collecting the corresponding eluate to obtain a single rare earth element europium, then eluting with 12 mL of 1.1 mol / L hydrochloric acid and collecting the corresponding eluate to obtain a single rare earth element gadolinium; The first exchange column is an ion exchange column filled with 2 mL of AG 50W-X12 resin, and the second exchange column is an ion exchange column filled with 2.5 mL of TODGA resin.

2. The sequential separation and purification method according to claim 1, characterized in that: The rare earth ore sample after digestion is obtained by a hydrofluoric acid-nitric acid closed pressure acid dissolution method.

3. The sequential separation and purification method according to claim 1, characterized in that: The pre-cleaning in step (2) includes: pre-cleaning the first exchange column with 30 mL of 6 mol / L nitric acid solution, 5 mL of pure water and 30 mL of 6 mol / L hydrochloric acid.

4. The sequential separation and purification method according to claim 1, characterized in that: The pre-cleaning in step (4) includes: pre-cleaning the second exchange column with 5 mL of pure water and 20 mL of a 0.02 mol / L hydrochloric acid solution.

Images