Ytterbium and lutetium element separation method

Abstract

The invention relates to a method for separating ytterbium and lutetium elements. The method comprises the following steps: mixing a chloride salt I and a chloride salt II, heating and melting the mixture, and obtaining a binary mixed molten salt III, wherein the chloride salt I is NaCl, LiCl or KCl, and the chloride salt II is CaCl2 or NaCl; dissolving an oxide or halide of ytterbium and lutetium in the molten molten salt III, and obtaining a mixed molten salt IV containing ytterbium ions and lutetium ions; inserting an electrode assembly into the molten mixed molten salt IV, connecting the assembly to an electrochemical workstation, and measuring the reduction potential A of the ytterbium ions and the reduction potential B of the lutetium ions by an electrochemical method; and controlling an electrolysis voltage C to perform electrolysis, utilizing the difference in reduction potentials of the ytterbium ions and the lutetium ions in the mixed molten salt IV, so that the electrolysis product, elemental lutetium, is adsorbed on the surface of a working electrode to obtain a high-lutetium product. According to the ytterbium and lutetium element separation method of the present invention, a molten salt electrochemical separation method is adopted, and the huge difference in the redox behavior of trivalent ytterbium and lutetium ions in molten salt III is utilized to achieve electrochemical separation of ytterbium and lutetium.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering and separation technology, and more particularly to a method for separating ytterbium and lutetium elements. Background Art

[0002] Rare earth elements, including ytterbium and lutetium, and their compounds possess numerous unique optical, electrical, and magnetic properties, leading to their widespread application in chemical engineering, medicine, catalysis, ceramics, and other fields. Radioactive isotopes of some rare earth elements also hold great promise in the preparation and application of radiopharmaceuticals. For example, lutetium-177, combined with various targeting molecules, is a widely recognized revolutionary approach for treating a variety of systemic metastatic malignancies. Therefore, the efficient separation and enrichment of rare earth elements is crucial. For example, the production of unsupported lutetium-177 requires separation of the raw ytterbium and the lutetium product.

[0003] Because rare earth elements have extremely similar chemical properties, they often appear as mixtures, making effective separation difficult. Ytterbium and lutetium are typically extracted using active electrodes or ion co-deposition electrolysis in a molten salt system, but only produce alloy products such as lutetium and ytterbium. For example, CN102628131B discloses an aluminum-lutetium-ytterbium alloy and its molten salt electrolysis preparation method. Traditional separation methods for separating ytterbium and lutetium primarily utilize the differences in the chemical properties of ytterbium and lutetium ions in aqueous solution, employing extractants for solution extraction and separation, including direct solution extraction or extraction chromatography. Since the separation coefficient is basically 1.5-2.6 (see Yang Fengli, Deng Zuoguo, Xu Tinghua. Analysis and comparison of the optimized process of extraction and separation of thulium, ytterbium and lutetium enrichments with the traditional process [J]. Journal of Jiangxi University of Science and Technology, 2007, 28(3): 6-9), which is relatively low, multi-stage and multi-step extraction is required, and a large amount of organic matter and solvents such as resins and extractants are used in the separation process. In addition, there are many factors affecting the separation efficiency, such as acidity and temperature. For example, CN201710344695.9 discloses a method for extracting and separating thulium, ytterbium and lutetium, and CN201810933476.9 discloses an extraction and separation method for co-producing 4N dysprosium and 4N ytterbium, and CN201910660087.8 discloses a method for solvent extraction and separation of thulium, ytterbium and lutetium enrichments. The separation process has many operations, generates a large amount of waste, and the materials used are expensive and the cost is high. Summary of the Invention

[0004] In order to solve the problems of multiple stages and steps, complicated operation, high cost, large amount of waste generation, etc. in the above-mentioned prior art separation of rare earth elements ytterbium and lutetium through processes such as organic solvent extraction or ion exchange chromatography, the present invention provides a method for separating ytterbium and lutetium elements.

[0005] According to the present invention, the method for separating ytterbium and lutetium elements includes the following steps: S1, mixing a chloride salt I and a chloride salt II and then heating and melting them to obtain a binary mixed molten salt III, wherein the chloride salt I is NaCl, LiCl or KCl, and the chloride salt II is CaCl2 or NaCl; S2, dissolving an oxide or halide of ytterbium and lutetium in the molten molten salt III to obtain a mixed molten salt IV containing ytterbium ions and lutetium ions; S3, inserting an electrode assembly into the molten mixed molten salt IV, connecting it to an electrochemical workstation, and measuring the reduction potential A of the ytterbium ions and the reduction potential B of the lutetium ions by an electrochemical method; S4, controlling the electrolysis voltage C to perform electrolysis, utilizing the difference in reduction potential of ytterbium ions and lutetium ions in the mixed molten salt IV, and adsorbing the electrolysis product, elemental lutetium, on the surface of the working electrode to obtain a high-lutetium product (the rest is the high-ytterbium molten salt).

[0006] Thus, unlike the traditional solvent extraction method that utilizes the distribution behavior of ions in different solvents, the present invention utilizes the difference in the reducibility of trivalent ytterbium and lutetium ions in chloride molten salt to achieve the electrochemical separation of ytterbium and lutetium elements. The difference is large and the separation is easy. Unlike the traditional solvent extraction method that requires multi-stage and multi-step separation operations, the electrolytic separation process of the present invention can be completed in just one step, with fewer process parameters and simple electrolytic equipment operation. Unlike the traditional solvent extraction method that requires a large amount of water, organic solvents and expensive extractants, the separation process will produce a large amount of waste and the separation cost is high. The materials and reagents used in the present invention are inexpensive and recyclable, resulting in less waste and low separation costs.

[0007] In a preferred embodiment, chloride salt I is NaCl, chloride salt II is CaCl2, and binary molten salt III is NaCl-CaCl2. In another preferred embodiment, chloride salt I is LiCl, chloride salt II is NaCl, and binary molten salt III is LiCl-NaCl. In another preferred embodiment, chloride salt I is LiCl, chloride salt II is CaCl2, and binary molten salt III is LiCl-CaCl2. In another preferred embodiment, chloride salt I is KCl, chloride salt II is CaCl2, and binary molten salt III is KCl-CaCl2.

[0008] Preferably, in step S1, the mass ratio of salt I to salt II is 1:3-3:1. It should be understood that the melting point of the molten salt III obtained within this ratio range is low, which facilitates the implementation of subsequent steps.

[0009] Preferably, in step S1, the heating and melting temperature is between 550°C and 850°C. In a preferred embodiment, after mixing Salt I and Salt II, the mixture is heated to 800°C and maintained, and then the temperature is lowered to 550°C and maintained, to obtain molten salt III. In a preferred embodiment, Salt I and Salt II are mixed and placed in a corundum crucible, placed in a heating furnace, heated to 850°C and maintained for 2 hours, and then lowered to 550°C and maintained for 10 hours to obtain molten salt III.

[0010] Preferably, when the object to be separated is an oxide of ytterbium and lutetium, i.e., ytterbium oxide and lutetium oxide, step S2 comprises: mixing molten salt III, ytterbium oxide and lutetium oxide and heating until molten salt III is melted, adding a co-solvent to convert it into a chloride of ytterbium and lutetium oxide and then dissolving it in molten salt III to obtain a mixed molten salt IV. Preferably, the mass fraction of ytterbium oxide and lutetium oxide in molten salt III is 0.1-10wt%. It should be understood that the range of this mass fraction helps to ensure the chlorination conversion effect of the oxide and ensure the final separation effect. Preferably, the co-solvent is NH4Cl or AlCl3. More preferably, the co-solvent is NH4Cl. Preferably, the mass ratio range of the co-solvent to the ytterbium oxide and lutetium oxide mixture is 2-5. It should be understood that this mass ratio range helps to ensure the chlorination conversion effect of the oxide and avoid excessive corrosion of the equipment without wasting the co-solvent. In a preferred embodiment, the molten salt III, ytterbium oxide and lutetium oxide are mixed and placed in a corundum crucible, which is then placed in a heating furnace and heated to 550-850°C. After holding the temperature for 1 hour, the corundum crucible is removed and a co-solvent is immediately added to the crucible. The mixture is stirred while hot, the crucible cover is covered, and the mixture is placed in a heating furnace again to keep the molten salt in a molten state and hold the temperature for 12 hours, so that the oxides are fully dissolved in the molten salt III, thereby obtaining a mixed molten salt IV. In this way, according to the method of the present invention, the insoluble ytterbium oxide and lutetium oxide can be converted into chlorides by the co-solvent and dissolved in the molten salt, and then separated by electrolytic deposition in the chloride molten salt to obtain a high-lutetium product. In particular, there is no need to use a large amount of acid to dissolve the oxides in advance to convert them into soluble chlorides, as in solvent extraction separation. The present invention can directly convert the insoluble rare earth oxides into chlorides by the co-solvent in the molten salt phase and dissolve them in the molten salt, making the process green and environmentally friendly.

[0011] Preferably, when the substance to be separated is a halide of ytterbium and lutetium, that is, chloride or fluoride of ytterbium and lutetium, step S2 includes directly dissolving ytterbium chloride, lutetium chloride, ytterbium fluoride or lutetium fluoride in the molten salt III to obtain a mixed molten salt IV.

[0012] Preferably, in step S3, the electrode assembly consists of a working electrode, a counter electrode and a reference electrode. In a preferred embodiment, the working electrode is a tungsten wire, a molybdenum wire or a platinum wire, preferably metal tungsten. In a preferred embodiment, the counter electrode is a graphite rod or a platinum rod, preferably graphite. In a preferred embodiment, the reference electrode is a platinum wire or Ag / AgCl, preferably metal platinum. Preferably, in step S3, a cyclic voltammetry curve is measured by the electrode assembly, thereby obtaining the reduction potential A of the ytterbium ion and the reduction potential B of the lutetium ion. In a preferred embodiment, the reduction potential A of the ytterbium ion is -0.20V, and the reduction potential B of the lutetium ion is -1.81V. It should be understood that the reduction potential here is an approximate relative value, which mainly depends on the reference electrode used, and the absolute value of the potential is not important.

[0013] Preferably, in step S4, the electrolysis method is constant voltage electrolysis. Preferably, in step S4, the electrolysis time is 0.5-12 hours. Preferably, in step S4, the electrolysis voltage C is more than 50mV lower than the reduction potential B and is higher than the decomposition voltage of the molten salt III. In a preferred embodiment, the electrolysis voltage is -1.86V and the electrolysis time is 12 hours. It should be understood that the decomposition voltage of the molten salt III is a property of the molten salt, and different chemical compositions have different potentials. The specific value is related to the chemical composition of the molten salt and the reference electrode used.

[0014] Preferably, the ytterbium and lutetium element separation method further comprises step S5, immersing the high-lutetium product in water to clean and remove the molten salt.

[0015] Preferably, the ytterbium and lutetium element separation method further includes step S6, dissolving the cleaned high-lutetium product in an acid solution to obtain a lutetium-containing aqueous solution. Preferably, the acid solution can be a common acid solution such as hydrochloric acid, nitric acid, or sulfuric acid. It should be understood that, depending on the type of acid solution, the lutetium-containing aqueous solution here can be an aqueous solution of lutetium chloride, lutetium sulfate, or lutetium nitrate.

[0016] Preferably, after diluting the lutetium-containing aqueous solution and performing elemental analysis, the lutetium-ytterbium content ratio in the high-lutetium product is increased to 99-120:1 relative to the lutetium-ytterbium content ratio of 1:1 in the product to be separated. Preferably, elemental analysis is performed using ICP-AES.

[0017] The ytterbium and lutetium element separation method of the present invention utilizes a molten salt electrochemical separation method, utilizing the significant differences in the redox behaviors of trivalent ytterbium and lutetium ions in molten salt III to achieve electrochemical separation of ytterbium and lutetium. Compared to prior art processes such as solvent extraction or ion exchange chromatography, which require large amounts of water and organic solvents, the ytterbium and lutetium element separation method of the present invention generates less waste. Compared to prior art processes such as solvent extraction or ion exchange chromatography, which suffer from low separation coefficients and cumbersome operations, the electrochemical separation process involved in the ytterbium and lutetium element separation method of the present invention is simple to operate, uses inexpensive and recyclable materials and reagents, requires simple equipment, has a short separation time, high efficiency, uses inexpensive and recyclable materials and reagents, requires simple equipment, and reduces separation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of an experimental device for a method for separating ytterbium and lutetium elements according to a preferred embodiment of the present invention.

[0019] Figure 2 These are the cyclic voltammetry curves of NaCl-CaCl2 molten salt and NaCl-CaCl2-YbCl3 (0.5wt%) molten salt on a tungsten electrode at 550°C.

[0020] Figure 3 These are the cyclic voltammetry curves of NaCl-CaCl2 molten salt and NaCl-CaCl2-LuCl3 (0.5wt%) molten salt at 550℃ on a tungsten electrode.

[0021] Figure 4 These are the cyclic voltammetry curves of NaCl-CaCl2 molten salt and NaCl-CaCl2-LuCl3 (0.5wt%)-YbCl3 (0.5wt%) molten salt on a tungsten electrode at 550°C. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0023] like Figure 1 As shown, the electrolytic separation device of the ytterbium and lutetium element separation method according to a preferred embodiment of the present invention includes an electric heating furnace 4 sealed by a nut with a stainless steel cover plate 8, an argon inlet 3 and an argon outlet 9 arranged on both sides of the stainless steel cover plate 8, a corundum gasket 7 placed in the electric heating furnace 4, a corundum crucible 5 loaded with a molten salt electrolyte 6, three stainless steel electrode rods 1 fixed on the stainless steel cover plate 8, insulated from the stainless steel cover plate 8 by a corundum tube 2, a tungsten wire working electrode 10 fixed at the bottom of the three stainless steel electrode rods 1 and extending into the molten salt electrolyte 6, a graphite auxiliary electrode 11 and a platinum wire reference electrode 12.

[0024] Example 1

[0025] Weigh 50g of NaCl and 100g of CaCl2, mix them evenly, and place them in a corundum crucible. Place it in a heating furnace and heat it to 850℃ and keep it for 2 hours, then reduce the temperature to 550℃ and keep it for 10 hours to obtain NaCl-CaCl2 molten salt.

[0026] Weigh 30.05 g of NaCl-CaCl2 molten salt, 0.032 g of ytterbium oxide, and 0.031 g of lutetium oxide into a corundum crucible, place it in a heating furnace and heat it to 850°C. After keeping warm for 1 hour, take out the corundum crucible and immediately add 0.35 g of the solvent NH4Cl into the crucible. Stir while hot, cover the crucible, and place it in the heating furnace again and keep warm for 12 hours to allow the oxides to fully dissolve in the molten salt to obtain NaCl-CaCl2 molten salt containing ytterbium and lutetium ions.

[0027] The electrode assembly consisting of tungsten wire, platinum wire and graphite rod was inserted into the molten salt and connected to the electrochemical workstation, wherein the tungsten wire was used as the working electrode 10 (see Figure 1 ), graphite rod as the counter electrode 11 (see Figure 1 ), platinum wire as reference electrode 12 (see Figure 1 ), and measured its cyclic voltammetry curve. The cyclic voltammetry curves of NaCl-CaCl2 molten salt and NaCl-CaCl2-YbCl3 (0.5wt%) molten salt on tungsten electrode at 550℃ are as follows Figure 2 As shown, it can be determined that the reduction potential A of the ytterbium element is -0.20V; the cyclic voltammetry curves of NaCl-CaCl2 molten salt and NaCl-CaCl2-LuCl3 (0.5wt%) molten salt at 550℃ on the tungsten electrode are as follows Figure 3 As shown, it can be determined that the reduction potential B of lutetium is -1.81V; the cyclic voltammetry curves of NaCl-CaCl2 molten salt and NaCl-CaCl2-LuCl3 (0.5wt%)-YbCl3 (0.5wt%) molten salt at 550℃ on the tungsten electrode are as follows Figure 4 As shown, by comparing Figure 4 The curve of ytterbium-lutetium mixed salt and Figure 2 Single ytterbium salt and Figure 3 From the curve of single lutetium salt, it can be seen that the potential value in the mixed system has not changed.

[0028] The electrolysis voltage was set to -2.00 V and the electrolysis time was set to 0.5 h.

[0029] After the electrolysis is complete, the elemental lutetium product, adsorbed onto the surface of the tungsten filament electrode, yielding a product with a high lutetium content. This product is then immersed in ultrapure water for 30 minutes to remove molten salt from the electrode and product surfaces. The electrolytic product is diluted with acid and analyzed using ICP-AES. The lutetium:ytterbium ratio increases from 1:1 to 99:1. The lutetium aqueous solution contains less than 1 ppm sodium and 1.8 ppm calcium, with all other impurities below 1 ppb, achieving efficient separation of lutetium and ytterbium and extraction of lutetium.

[0030] Example 2

[0031] Weigh 100g of NaCl and 50g of CaCl2, mix them evenly, and place them in a corundum crucible. Place it in a heating furnace and heat it to 850℃ for 2 hours, then reduce the temperature to 550℃ and keep it for 10 hours to obtain NaCl-CaCl2 molten salt.

[0032] Weigh 30.01 g of NaCl-CaCl2 molten salt, 3.03 g of ytterbium oxide, and 3.02 g of lutetium oxide into a corundum crucible, place it in a heating furnace and heat it to 550°C. After keeping warm for 1 hour, take out the corundum crucible and immediately add 12.02 g of the solvent AlCl3 into the crucible. Stir while hot, cover the crucible with a cover plate, and place it in the heating furnace again and keep warm for 12 hours to allow the oxides to fully dissolve in the molten salt to obtain NaCl-CaCl2 molten salt containing ytterbium and lutetium ions.

[0033] Electrode assemblies consisting of a molybdenum wire, Ag / AgCl, and a platinum rod were respectively inserted into the above-mentioned molten salt and connected to an electrochemical workstation, with the molybdenum wire serving as the working electrode, the platinum rod serving as the counter electrode, and the Ag / AgCl serving as the reference electrode. Cyclic voltammetry curves were measured, and the reduction potentials A and B of ytterbium were determined to be -0.20 V and -1.81 V, respectively.

[0034] The electrolysis voltage was set to -1.86 V and the electrolysis time was set to 12 hours.

[0035] After the electrolysis is complete, the electrolysis product adsorbs onto the surface of the molybdenum wire electrode, yielding a product with a high lutetium content. This product is then immersed in ultrapure water for 30 minutes to remove molten salt from the electrode and product surfaces. The electrolysis product is diluted with acid and analyzed using ICP-AES. The lutetium:ytterbium ratio increases from 1:1 to 120:1, with both Na and Ca levels in the lutetium product below 1 ppm, and all other impurities below 1 ppb, achieving efficient separation and extraction of lutetium.

[0036] Example 3

[0037] Weigh 150 g of LiCl and 50 g of NaCl, mix them evenly, and place them in a corundum crucible. Place the crucible in a heating furnace and heat it to 850°C for 2 hours, then reduce the temperature to 650°C and keep it for 10 hours to obtain LiCl-NaCl molten salt.

[0038] Weigh 30.00 g of LiCl-NaCl molten salt, 3.01 g of ytterbium oxide, and 3.00 g of lutetium oxide into a corundum crucible, place it in a heating furnace and heat it to 750°C. After keeping warm for 1 hour, take out the corundum crucible and immediately add 12.04 g of the solvent AlCl3 into the crucible. Stir while hot, cover the crucible, and place it in the heating furnace again and keep warm for 12 hours to allow the oxides to fully dissolve in the molten salt to obtain LiCl-NaCl molten salt containing ytterbium and lutetium ions.

[0039] Electrode assemblies consisting of a platinum wire, Ag / AgCl, and a graphite rod were respectively inserted into the above-mentioned molten salt and connected to an electrochemical workstation, with the platinum wire serving as the working electrode, the graphite rod serving as the counter electrode, and the Ag / AgCl serving as the reference electrode. Cyclic voltammetry curves were measured, and the reduction potentials A and B of ytterbium were determined to be -0.25 V and -1.87 V, respectively.

[0040] The electrolysis voltage was set to -1.95 V and the electrolysis time was set to 12 hours.

[0041] After the electrolysis is complete, the electrolysis product adsorbs onto the surface of the platinum wire electrode, yielding a product with a high lutetium content. This product is then immersed in ultrapure water for 30 minutes to remove molten salt from the electrode and product surfaces. The electrolysis product is diluted with acid and analyzed using ICP-AES. The lutetium:ytterbium ratio increases from 1:1 to 100:1, with both Na and Li levels in the lutetium product below 1 ppm, and all other impurities below 1 ppb, achieving efficient separation of lutetium and ytterbium and extraction of lutetium.

[0042] Example 4

[0043] Weigh 50g of LiCl and 150g of CaCl2, mix them evenly, place them in a corundum crucible, put them in a heating furnace, heat them to 850℃ and keep them warm for 2 hours, then reduce the temperature to 650℃ and keep them warm for 10 hours to obtain LiCl-CaCl2 molten salt.

[0044] Weigh 30.00 g of LiCl-CaCl2 molten salt, 3.00 g of ytterbium oxide, and 3.03 g of lutetium oxide into a corundum crucible, place it in a heating furnace and heat it to 650°C. After keeping warm for 1 hour, take out the corundum crucible and immediately add 12.01 g of the solvent AlCl3 into the crucible. Stir while hot, cover the crucible, and place it in the heating furnace again and keep warm for 12 hours to allow the oxides to fully dissolve in the molten salt to obtain LiCl-CaCl2 molten salt containing ytterbium and lutetium ions.

[0045] An electrode assembly consisting of a tungsten wire, a platinum wire, and a graphite rod was respectively inserted into the above-mentioned molten salt and connected to an electrochemical workstation, with the tungsten wire as the working electrode, the graphite rod as the counter electrode, and the platinum wire as the reference electrode. The cyclic voltammetry curves were measured, and the reduction potential A of the ytterbium element was determined to be -0.22 V, and the reduction potential B of the lutetium element was determined to be -1.85 V.

[0046] The electrolysis voltage was set to -1.95 V and the electrolysis time was set to 12 hours.

[0047] After the electrolysis is complete, the electrolysis product adsorbs onto the surface of the tungsten filament electrode, yielding a product with a high lutetium content. This product is then immersed in ultrapure water for 30 minutes to remove molten salt from the electrode and product surfaces. The electrolysis product is diluted with acid and analyzed using ICP-AES. The lutetium:ytterbium ratio increases from 1:1 to 110:1, with the Li and Ca contents in the lutetium product both below 1 ppm, and all other impurities below 1 ppb, achieving efficient separation of lutetium and ytterbium and extraction of lutetium.

[0048] Example 5

[0049] Weigh 150g of LiCl and 50g of CaCl2, mix them evenly, place them in a corundum crucible, put them in a heating furnace, heat them to 850℃ and keep them warm for 2 hours, then reduce the temperature to 650℃ and keep them warm for 10 hours to obtain LiCl-CaCl2 molten salt.

[0050] Weigh 30.01 g of LiCl-CaCl2 molten salt, 3.01 g of ytterbium oxide, and 3.02 g of lutetium oxide into a corundum crucible, place it in a heating furnace and heat it to 650°C. After keeping warm for 1 hour, take out the corundum crucible and immediately add 12.03 g of the solvent AlCl3 into the crucible. Stir while hot, cover the crucible, and place it in the heating furnace again and keep warm for 12 hours to allow the oxides to fully dissolve in the molten salt to obtain LiCl-CaCl2 molten salt containing ytterbium and lutetium ions.

[0051] An electrode assembly consisting of a tungsten wire, a platinum wire, and a graphite rod was respectively inserted into the above-mentioned molten salt and connected to an electrochemical workstation, wherein the tungsten wire served as the working electrode, the graphite rod served as the counter electrode, and the platinum wire served as the reference electrode. The cyclic voltammetry curves were measured, and the reduction potential A of the ytterbium element was determined to be -0.25 V, and the reduction potential B of the lutetium element was determined to be -1.89 V.

[0052] The electrolysis voltage was set to -2.00 V and the electrolysis time was set to 12 hours.

[0053] After the electrolysis is complete, the electrolysis product adsorbs onto the surface of the tungsten filament electrode, yielding a product with a high lutetium content. This product is then immersed in ultrapure water for 30 minutes to remove molten salt from the electrode and product surfaces. The electrolysis product is diluted with acid and analyzed using ICP-AES. The lutetium:ytterbium ratio increases from 1:1 to 105:1, with the Li and Ca contents in the lutetium product both below 1 ppm, and all other impurities below 1 ppb, achieving efficient separation of lutetium and ytterbium and extraction of lutetium.

[0054] Example 6

[0055] Weigh 150g of KCl and 50g of CaCl2, mix them evenly, and place them in a corundum crucible. Place them in a heating furnace and heat them to 850℃ for 2 hours, then reduce the temperature to 650℃ and keep them for 10 hours to obtain KCl-CaCl2 molten salt.

[0056] Weigh 30.05 g of KCl-CaCl2 molten salt, 3.01 g of ytterbium oxide, and 3.01 g of lutetium oxide into a corundum crucible, place it in a heating furnace and heat it to 700°C. After keeping warm for 1 hour, take out the corundum crucible and immediately add 12.05 g of the solvent AlCl3 into the crucible. Stir while hot, cover the crucible, and place it in the heating furnace again and keep warm for 12 hours to allow the oxides to fully dissolve in the molten salt. KCl-CaCl2 molten salt containing ytterbium and lutetium ions is obtained.

[0057] An electrode assembly consisting of a tungsten wire, a platinum wire, and a graphite rod was respectively inserted into the above-mentioned molten salt and connected to an electrochemical workstation, with the tungsten wire serving as the working electrode, the graphite rod serving as the counter electrode, and the platinum wire serving as the reference electrode. The cyclic voltammetry curves were measured, and the reduction potential A of the ytterbium element was determined to be -0.26 V, and the reduction potential B of the lutetium element was determined to be -1.88 V.

[0058] The electrolysis voltage was set to -1.95 V and the electrolysis time was set to 12 hours.

[0059] After electrolysis, the electrolysis product adsorbed onto the surface of the tungsten filament electrode, yielding a product with a high lutetium content. This product was then immersed in ultrapure water for 30 minutes to remove molten salt from the electrode and product surfaces. The electrolysis product was dissolved and diluted with acid before elemental analysis using ICP-AES. The lutetium:ytterbium ratio increased from 1:1 to 102:1, with K and Ca levels in the lutetium product both below 1 ppm, and all other impurities below 1 ppb, achieving efficient separation of lutetium and ytterbium and extraction of lutetium.

[0060] Comparative Example 1

[0061] Prepare a standard solution of ytterbium and lutetium elements (feed solution): Dissolve ytterbium oxide and lutetium oxide in a 1:1 hydrochloric acid solution, evaporate to near dryness, and dilute to a desired volume with dilute hydrochloric acid to a pH of 1. The concentrations of both ytterbium oxide and lutetium oxide are 0.06 mol / L (approximately 1 wt%).

[0062] Preparation of the chromatography column: A column with a heat-insulating jacket, 60.8 cm in height and 0.82 cm in inner diameter, was used. Dry packing was performed by soaking the column in 4 mol / L hydrochloric acid to remove iron, and then washing the column with deionized water.

[0063] Add 0.5 mL of the ytterbium-lutetium solution, maintain a flow rate of 0.5 cm / min, and maintain the column temperature at 50°C. Elute the ytterbium and lutetium with 2.5 mol / L hydrochloric acid. Collect the effluent. Elemental analysis using ICP-AES reveals that the lutetium:ytterbium ratio increases from 1:1 to 1.5:1.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications are possible. In other words, any simple, equivalent changes and modifications made in accordance with the claims and description of the present invention are within the scope of protection of the patent claims. Anything not fully described in this invention constitutes conventional technology.

Claims

1. A method for separating ytterbium and lutetium elements, characterized in that: The ytterbium and lutetium element separation method comprises the following steps: S1, mixing a chloride salt I and a chloride salt II and heating and melting them to obtain a binary mixed molten salt III, wherein the chloride salt I is NaCl, LiCl or KCl, the chloride salt II is CaCl2 or NaCl, the mass ratio of salt I to salt II is 1:3-3:1, and the heating and melting temperature is between 550-850°C; S2, mixing molten salt III, ytterbium oxide, and lutetium oxide, and heating until molten salt III is melted, adding a co-solvent to convert it into ytterbium-lutetium chloride, and then dissolving it in molten salt III; or dissolving ytterbium-lutetium halide in molten salt III to obtain a mixed molten salt IV containing ytterbium ions and lutetium ions; S3, inserting the electrode assembly into the molten mixed molten salt IV, connecting it to an electrochemical workstation, and measuring the reduction potential A of the ytterbium ion and the reduction potential B of the lutetium ion using an electrochemical method, wherein the electrode assembly consists of a working electrode, a counter electrode, and a reference electrode; S4, controlling the electrolysis voltage C for electrolysis, utilizing the difference in reduction potentials between ytterbium ions and lutetium ions in the mixed molten salt IV, and adsorbing the electrolysis product elemental lutetium on the surface of the working electrode to obtain a high-lutetium product, wherein the electrolysis method is constant voltage electrolysis, and the electrolysis voltage C is controlled to be more than 50 mV lower than the reduction potential B, and at the same time higher than the decomposition voltage of the molten salt III.

2. The method for separating ytterbium and lutetium elements according to claim 1, wherein The cosolvent is NH4Cl or AlCl3.

3. The method for separating ytterbium and lutetium elements according to claim 1, wherein: The ytterbium and lutetium element separation method further includes step S5, immersing the high-lutetium product in water to clean and remove the molten salt.

4. The method for separating ytterbium and lutetium elements according to claim 3, wherein: The method for separating ytterbium and lutetium elements further includes step S6, dissolving the cleaned high-lutetium product in an acid solution to obtain a lutetium-containing aqueous solution.

5. The method for separating ytterbium and lutetium elements according to claim 4, wherein: Elemental analysis was performed after diluting the lutetium-containing aqueous solution, and the lutetium-ytterbium content ratio increased from 1:1 to 99-120:1.

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