A zirconium and hafnium separation method based on crown ether complex regulator control electrophoretic migration behavior

Abstract

The application belongs to the technical field of rare metal hydrometallurgy, and particularly discloses a zirconium and hafnium separation method based on crown ether complex additive regulation of electrophoretic migration behavior. The zirconium and hafnium separation method first performs acid dissolution on raw materials containing zirconium and hafnium to obtain an acidic zirconium and hafnium mixed solution. By introducing a crown ether complex additive, the apparent charge density, solvation radius, aggregation scale, Zeta potential or shape factor of zirconium and hafnium hydrolysis polymers, complexes, colloidal particles or other charged species are changed, so that the zirconium species and the hafnium species produce a distinguishable migration difference in a direct current electric field, and then a zirconium enrichment phase and a hafnium enrichment phase are formed in different regions of an electrophoresis device, thereby realizing effective separation of the two. The zirconium and hafnium separation method realizes the purpose of separating zirconium and hafnium by electrophoresis, and can be used as an independent differential enrichment or pre-separation step in the zirconium and hafnium hydrometallurgical separation process, thereby simplifying the process flow, simplifying the equipment, and facilitating greenization and modularization.

Description

Technical Field

[0001] This invention belongs to the field of rare metal hydrometallurgical technology, specifically relating to a method for differential enrichment and separation of zirconium and hafnium by regulating the apparent electrophoretic migration behavior of zirconium and hafnium in acidic aqueous phases through crown ether complex additives. Background Technology

[0002] Zirconium and hafnium, as important strategic rare metals, hold an irreplaceable position in modern high-tech and defense industries. High-purity zirconium, with its excellent corrosion resistance and low thermal neutron absorption cross-section, has become a key material for nuclear reactor fuel cladding and core structural components; while high-purity hafnium, due to its outstanding thermal neutron trapping ability, is widely used in the manufacture of control rods for nuclear-powered ships and space reactors. Therefore, the demand for these two materials is extremely significant.

[0003] However, both zirconium and hafnium belong to Group IVB and have very similar ionic radii, valence states, and hydrolysis coordination behaviors. They are usually found together in natural zirconium ores and their chlorine oxide, sulfate, and nitrate systems. Nuclear-grade zirconium requires extremely low hafnium content, while hafnium materials require controlled zirconium impurities. Therefore, zirconium-hafnium separation is a crucial step in the preparation of nuclear materials and high-purity rare metals.

[0004] Existing industrial methods for zirconium-hafnium separation mainly include MIBK-thiocyanate extraction, TBP / phosphate ester system extraction, ion exchange, and molten salt distillation. While these methods can achieve high-purity separation, they generally suffer from problems such as multiple process stages, high consumption of organic phase, complex waste liquid treatment, high equipment investment, or difficulty in adapting to small- to medium-scale flexible production.

[0005] Electrophoresis offers advantages such as simple equipment, ambient temperature and pressure operation, ease of continuous operation, and easy coupling with aqueous systems, making it a preferred method for metal separation. However, zirconium and hafnium have the same valence state in ordinary acidic aqueous solutions, exhibiting similar hydrolysis and coordination behaviors. The electrophoretic migration differences between their free ions or simple hydrated ions are minimal, and applying an electric field alone is usually insufficient to create practically valuable component differences. Consequently, electrophoresis cannot yet be effectively applied to the separation of zirconium and hafnium.

[0006] Therefore, developing a novel aqueous phase separation method using electrophoresis is of great significance. Summary of the Invention

[0007] To address the numerous problems existing in current zirconium-hafnium separation methods, and the fact that electrophoresis cannot be effectively applied to zirconium-hafnium separation, the inventors of this invention, based on their research on zirconium-hafnium separation, propose a novel method for zirconium-hafnium separation based on the regulation of electrophoretic migration behavior using crown ether complexes as auxiliaries. This method, by introducing crown ether complexes as auxiliaries, alters the apparent charge density, solvation radius, aggregation scale, zeta potential, or shape factor of zirconium-hafnium hydrolysates, complexes, colloidal particles, or other charged species. This results in distinguishable migration differences between zirconium and hafnium species in a DC electric field, thereby forming zirconium-enriched and hafnium-enriched phases in different regions of the electrophoresis apparatus, achieving effective separation of the two species.

[0008] The present invention specifically adopts the following technical solution: A method for separating zirconium and hafnium based on the regulation of electrophoretic migration behavior by crown ether complex auxiliaries includes the following steps: S1. Dissolve the raw materials containing zirconium and hafnium in an acidic medium to prepare a zirconium-hafnium mixed solution; wherein the total metal ion concentration of the zirconium-hafnium mixed solution is 0.3 mol / L~0.8 mol / L, expressed as the total molar concentration of Zr and Hf; S2. Add crown ether complex additives to the zirconium-hafnium mixture and adjust the apparent pH of the obtained mixture to 1.0~2.0 to obtain an electrophoretic feed solution containing zirconium and hafnium species; S3. The electrophoresis solution is introduced into the electrophoresis apparatus and electrophoresed for 5 min to 15 min under a DC electric field strength of 1.3 V / cm to 6.7 V / cm, so that zirconium species and hafnium species undergo differential migration in the electric field. S4. After electrophoresis, turn off the power and keep the electrophoresis apparatus still for 30 to 120 seconds. Then, take liquid samples in segments along the direction of the electric field, collecting the zirconium-enriched phase near the anode and the hafnium-enriched phase near the cathode. The zirconium-enriched phase refers to the liquid near the anode where the Zr:Hf mass ratio is higher than the corresponding Zr:Hf mass ratio in the electrophoresis feed solution. The hafnium-enriched phase refers to the liquid near the cathode where the Zr:Hf mass ratio is lower than the corresponding Zr:Hf mass ratio in the electrophoresis feed solution.

[0009] In step S1, controlling the total metal ion concentration within a suitable range is primarily to ensure that the subsequent electrophoresis solution has appropriate clarity, conductivity, and migration stability. If the total metal ion concentration is too low, the difference between the components at both ends after electrophoresis will be weak; if the total metal ion concentration is too high, it may lead to an increase in the viscosity, conductivity, Joule heat, or degree of colloidal aggregation of the solution, thereby reducing the stability of electrophoretic migration. Therefore, under the acidity, crown ether complex concentration, electric field strength, and electrophoresis time conditions described in this invention, it is preferable to control the total metal ion concentration within the range of 0.3 mol / L to 0.8 mol / L, preferably within the range of 0.4 mol / L to 0.6 mol / L.

[0010] In steps S1 and S2, the zirconium-hafnium mixture and electrophoresis solution should be clear, free of obvious precipitates or large suspended particles, and maintain a stable migration state during electrophoresis. If, after adding crown ether complex additives and adjusting the apparent pH, the obtained electrophoresis solution exhibits obvious turbidity, flocculation, or precipitation, or if abnormal current fluctuations, rapid temperature rise, excessive bubble generation, or significant surface disturbance occur during electrophoresis, the zirconium-hafnium mixture can be diluted with an acidic medium with the same acidity as the zirconium-hafnium mixture or electrophoresis solution to adjust the total metal ion concentration from 0.3 mol / L to 0.8 mol / L to a lower concentration. After dilution, crown ether complex additives should be added again and the apparent pH adjusted to 1.0 to 2.0 to restore the electrophoresis solution to meet the conditions described in step S2 before electrophoresis is performed again. The above adjustments are fundamentally aimed at ensuring the clarity, conductivity, and migration stability of the electrophoresis solution.

[0011] Generally, in step S1, the acidic medium can be selected from conventional acid solvents such as hydrochloric acid. There is no particular limitation here, but the purpose is to dissolve the raw materials containing zirconium and hafnium to obtain a zirconium-hafnium mixture.

[0012] Optionally, in step S2, the crown ether complex auxiliaries are selected from 15-crown-5, 18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6, and one or more of the hydroxyl, carboxyl, sulfonic acid, amide, phosphoxy, or polyether chain substituted derivatives of the above crown ethers.

[0013] For benzo-18-crown-6, dibenzo-18-crown-6, and their substituted derivatives, poor solubility in acidic aqueous phases may lead to decreased reproducibility due to uneven dispersion when used directly. Therefore, water-soluble substituted derivatives with hydroxyl, carboxyl, sulfonic acid, amide, phosphoxy, or polyether chain substitutions are preferred to improve their solubility or dispersion stability in acidic aqueous phases.

[0014] Furthermore, the crown ether complex adjuvant is preferably one or more of 18-crown-6, carboxyl-substituted 18-crown-6, sulfonic acid-substituted 18-crown-6, water-soluble substituted derivatives of benzo-18-crown-6, and water-soluble substituted derivatives of dibenzo-18-crown-6; more preferably, it is 18-crown-6.

[0015] In step S2, the concentration of the crown ether complex auxiliaries in the electrophoresis solution is 0.01 mol / L to 0.20 mol / L, preferably 0.03 mol / L to 0.10 mol / L, and more preferably 0.05 mol / L to 0.10 mol / L, based on the molar concentration of the crown ether molecules.

[0016] In step S2, for systems with high ionic strength or unstable pH electrode readings, free acid concentration can be used to assist in characterizing acidity, but the acidity conditions should correspond to an apparent pH range of 1.0 to 2.0.

[0017] It should be noted that in step S2, the zirconium and hafnium ions in the zirconium-hafnium mixture will interact with the crown ether complex auxiliaries in the acidic system through one or more of the following mechanisms: coordination, hydrogen bonding, ion association, solvation layer regulation, or steric hindrance regulation, to form hydrolyzed polymers, complexes, colloidal particles, or other charged species. The zirconium and hafnium species formed will exhibit obvious apparent electrophoretic migration behavior.

[0018] Optionally, in step S3, the electrophoresis device can be a U-tube electrophoresis device, a horizontal tank electrophoresis device, a flat flow channel electrophoresis device, or an electrophoresis tank with a diaphragm; as long as the electrophoresis device can form a clear electric field direction and allow segmented collection of the end regions near the anode side and near the cathode side along the electric field direction, it can be used in this invention.

[0019] Optionally, in step S3, to reduce macroscopic backmixing caused by electrolytic bubbles, Joule heating, local convection, or liquid surface disturbance during electrophoresis, a conventional disturbance suppression structure can be set according to the specific form of the electrophoresis apparatus. The disturbance suppression structure includes one or more of a porous membrane, an inert porous plate, a laminar flow guide plate, or a laminar flow guide channel. This disturbance suppression structure is only used to maintain the stability of liquid migration and segmented liquid collection during electrophoresis; it does not use size sieving, filtration, or selective adsorption as a zirconium-hafnium separation mechanism, nor is it a necessary means for achieving differential enrichment of zirconium-hafnium in this invention.

[0020] Generally, in step S3, the electrodes in the electrophoresis apparatus can be platinum, titanium-based platinum, graphite, glassy carbon, titanium iridium oxide, or other acid-resistant and conductive materials in the prior art.

[0021] Generally, in step S3, a constant voltage, constant current, or constant electric field intensity mode can be used during electrophoresis to control the DC electric field intensity within the range of 1.3 V / cm to 6.7 V / cm, preferably 2.5 V / cm to 5.5 V / cm, as a characterization operating condition to avoid the problem of incomparable voltage parameters due to changes in electrode spacing.

[0022] In step S3, the control of the DC electric field strength during the electrophoresis process should ensure that a continuous bubble layer does not form on the electrode surface, and that there are no visible eddies, liquid surface agitation, or rapid back-mixing of liquids at both ends within the electrophoresis apparatus. If a continuous bubble layer, obvious eddies, liquid surface agitation, rapid back-mixing of liquids at both ends, or a single electrophoresis temperature rise exceeding 5°C occurs, it indicates insufficient migration stability under the electrophoresis conditions. In this case, the DC electric field strength should be adjusted to a lower value, preferably to the middle region within the range of 2.5 V / cm to 5.5 V / cm. This can be combined with adjustments such as reducing the current density, increasing the effective electrode area, using constant temperature cooling, pulsed electric fields, or setting up disturbance suppression structures to restore the stability requirements of the electrophoresis process.

[0023] Generally, in step S3, in order to maintain the smooth progress of the electrophoresis process, the temperature of the electrophoresis solution is controlled at 15℃~35℃ and the temperature rise of a single electrophoresis does not exceed 5℃.

[0024] Generally, in step S4, the time to stand for 30 s to 120 s is sufficient.

[0025] In step S4, the determination of the zirconium-enriched phase and the hafnium-enriched phase includes determining the regional attributes and the separation effect. The regional attribute determination refers to the following: the zirconium-enriched phase is located near the anode side, and its Zr:Hf mass ratio is higher than that of the electrophoresis feed solution before electrophoresis; the hafnium-enriched phase is located near the cathode side, and its Zr:Hf mass ratio is lower than that of the electrophoresis feed solution before electrophoresis. The separation effect determination refers to the following: the separation factor β between the two ends of the paired zirconium-enriched phase and hafnium-enriched phase is not less than 1.10, where β = (Zr:Hf) / (Zr:Hf). 锆富集相 / (Zr:Hf) 铪富集相When β is below 1.10, it is considered that only a weak component difference exists, and the liquid in this region is not considered the target enriched product of this invention. After electrophoresis, there is an intermediate region of liquid between the two enriched regions. This intermediate region of liquid refers to the liquid located between the zirconium-enriched phase and the hafnium-enriched phase, whose Zr:Hf mass ratio is close to that of the electrophoresis liquid before electrophoresis, or the liquid in the region that cannot make the separation factor β at both ends reach 1.10 when calculated in pairs with the corresponding end regions. The intermediate region of liquid is not considered the target enriched product of this invention and can be reused or combined as needed. For example, it can be combined with the zirconium-hafnium mixture, supplemented with acidic medium and crown ether complex additives, and readjusted to the electrophoresis liquid conditions.

[0026] Specifically, for the aforementioned optional electrophoresis apparatus with a clearly defined electric field direction and an end-enriched region, the zirconium-enriched phase can be taken from the end-enriched region near the anode, and the hafnium-enriched phase can be taken from the end-enriched region near the cathode. The end-enriched region can be determined according to the structure of the electrophoresis apparatus, the electric field direction, and the effective migration path, and is preferably the liquid within 0 to 15% of the effective migration distance of the corresponding electrode.

[0027] Taking a U-tube electrophoresis apparatus as an example, the zirconium-enriched phase can be taken from the liquid within 0-15% of the effective migration distance near the anode, and the hafnium-enriched phase can be taken from the liquid within 0-15% of the effective migration distance near the cathode. For horizontal tank electrophoresis apparatus, flat plate flow channel electrophoresis apparatus, or diaphragm electrophoresis tank, the above principles can be followed to collect the liquid in the end regions near the anode and cathode along the electric field direction as candidate zirconium-enriched phases and candidate hafnium-enriched phases, respectively. The specific liquid collection boundary is based on the fact that the collected end region liquid can meet the regional attribute determination of zirconium-enriched phase and hafnium-enriched phase and the separation factor β at both ends is not less than 1.10.

[0028] Furthermore, in the U-tube electrophoresis apparatus, the aforementioned effective migration distance refers to the length of the continuous liquid phase path along the electric field direction from the effective electrode boundary on the anode side to the effective electrode boundary on the cathode side; when the electrode spacing is used to characterize the electric field strength, this effective migration distance can be determined according to the distance between the effective working surfaces of the two electrodes.

[0029] Furthermore, the aforementioned percentages are calculated starting from the effective electrode boundary at the corresponding end and extending along the electric field direction towards the center of the device. As the sampling position continues to extend towards the central region, the zirconium enrichment factor decreases, therefore the liquid in the central region is not considered as the target enriched product.

[0030] When actually collecting liquid, one or more of the following methods can be used to collect the liquid in segments: clamping the connecting area, closing the separator valve, inserting a partition, using segmented liquid collection tubes, pipetting tubes, or pre-set sampling ports. It is not advisable to pour the liquid out as a whole to avoid back mixing.

[0031] After determining the enrichment regions at both ends, the zirconium-enriched phase is collected segmentally from the anode-side region, with a collection volume accounting for 10% to 30% of the anode-side region volume, preferably 20% to 25%. The hafnium-enriched phase is collected segmentally from the cathode-side region according to a corresponding proportion, with a collection volume accounting for 10% to 30% of the cathode-side region volume, preferably 20% to 25%. The corresponding proportion refers to the collection of the zirconium-enriched phase and the hafnium-enriched phase according to the volume ratio of their respective end regions, rather than calculated based on the total volume of the entire electrophoretic feed solution.

[0032] The zirconium-hafnium separation method provided by this invention first involves acid dissolving the raw materials containing zirconium and hafnium to obtain an acidic zirconium-hafnium mixture. In the acidic aqueous phase, zirconium and hafnium do not exist solely in a simple M... 4+ The presence of hydrated ions can lead to various forms of separation, including polynuclear hydrolytic polymers, hydroxyl-bridged cations, chloride complexes, or colloidal particles. Crown ether complex auxiliaries induce differential coordination, hydrogen bonding, ion association, surface adsorption, solvation layer regulation, or steric hindrance regulation of these species, resulting in differences in apparent charge, particle size, solvation radius, shape factor, or degree of counterion association. These differences translate into differences in macroscopic electrophoretic migration behavior. Based on this, differentiated electrophoretic behavior occurs under specific DC electric field strengths, avoiding reliance on the minute migration rate differences of zirconium and hafnium free ions themselves, thereby significantly improving the separation efficiency.

[0033] This invention does not require a specific mononuclear, multinuclear, tetranuclear, or octanuclear zirconium hafnium species structure as a necessary technical feature, nor does it limit itself to a fixed coordination constant or a single complex structure. The above explanation of the mechanism is only used to explain the possible separation effect of this invention and should not be construed as an expansion of the scope of protection of this invention. The method described in this invention uses the defined process conditions and separation effect as the boundaries of the technical solution.

[0034] The technical solution of the present invention has the following beneficial effects: 1) The zirconium-hafnium separation method provided by the present invention couples the regulation of crown ether complex additives with electrophoretic migration, which can amplify the apparent migration differences of zirconium and hafnium in acidic aqueous systems, improve the problem of small migration differences of zirconium and hafnium under simple electrophoretic conditions and the difficulty in forming obvious component differences, and achieve the purpose of effective separation of zirconium and hafnium by electrophoresis. 2) The zirconium-hafnium separation method provided by the present invention, by controlling the acidity of the electrophoresis solution, the type and concentration of crown ether complex additives, the DC electric field strength, the electrophoresis time, and the segmented liquid collection boundary, provides a foundation for the subsequent scale-up or continuous process development of the zirconium-hafnium separation method. 3) The zirconium-hafnium separation method provided by the present invention can be used as an independent differential enrichment or pre-separation step in the zirconium-hafnium wet separation process. It is used to regulate the composition of zirconium-hafnium mixture in an aqueous system. The process is relatively simplified, which helps to reduce the use of organic phase and the pressure of waste liquid treatment. 4) The zirconium-hafnium separation method provided by this invention is mainly carried out in an aqueous medium under normal temperature and pressure. The equipment is simple and has the potential for greening and modularization. Compared with mature processes such as MIBK-thiocyanate extraction, TBP / phosphate ester extraction, and molten salt distillation, the improvement of this invention is mainly reflected in: it does not require a large amount of organic phase or high-temperature molten salt system, and can achieve single-stage differential pre-enrichment under aqueous phase and normal temperature and pressure conditions. It is suitable for small- to medium-scale flexible treatment or as a pretreatment step before deep extraction / ion exchange, thereby reducing the load on subsequent processes, reducing organic phase consumption, and reducing waste liquid treatment pressure. Detailed Implementation

[0035] The technical solution of the present invention will be described and illustrated below with reference to embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] To avoid confusion of terminology, in this invention, "zirconium and hafnium-containing raw materials" refers to raw materials containing Zr and Hf; "zirconium-hafnium mixture" refers to the aqueous solution obtained by dissolving the above-mentioned zirconium and hafnium-containing raw materials in an acidic medium; and "electrophoretic feed" refers to the feed solution before entering the electrophoresis apparatus after adding crown ether complex additives to the zirconium-hafnium mixture and adjusting the acidity.

[0037] In this invention, the zirconium enrichment factor R is used to calculate the zirconium enrichment factor. Zr Hafnium enrichment factor R Hf Both the reference solutions for the separation factor β at both ends are electrophoretic solutions.

[0038] The following indicators are used in this invention to evaluate the separation effect of single-stage electrophoresis: Zirconium enrichment factor R Zr = (Zr / Hf) 锆富集相 / (Zr / Hf) 电泳料液 ; Hafnium enrichment factor R Hf = (Zr / Hf) 电泳料液 / (Zr / Hf) 铪富集相 ; The separation factor at both ends is β = (Zr / Hf) 锆富集相 / (Zr / Hf) 铪富集相 .

[0039] Wherein, β is the separation factor between the zirconium-enriched phase and the hafnium-enriched phase, characterizing the component difference between the two products after the same stage of electrophoresis, and is not equivalent to the single-end enrichment factor R of the zirconium-enriched phase or the hafnium-enriched phase relative to the electrophoretic feed solution. Zr or R Hf In this invention, when the separation factor β at both ends is less than 1.10, it is considered that only a weak component difference is formed; when β is not less than 1.10, it is considered that an acceptable zirconium-hafnium pre-enrichment effect is achieved; when β is 1.15~1.18, it is considered that a better single-stage electrophoretic pre-enrichment effect is achieved. The process parameter range of this invention is determined based on obtaining a separation effect with β not less than 1.10.

[0040] Unless otherwise specified, the Zr:Hf ratio in each embodiment and comparative example is a mass ratio.

[0041] In the following embodiments and comparative examples, in order to ensure the repeatability and operational stability of the electrophoresis process, voltage, current, temperature, bubble generation and liquid surface disturbance can be recorded during the electrophoresis process. If necessary, one or more of the following methods can be used: constant temperature water bath, jacket cooling, pulsed electric field or reduced current density, to reduce the influence of Joule heating and electrolytic bubbles on the electrophoretic separation effect.

[0042] Example 1 Weigh 80.65 g of raw material containing zirconium and hafnium, add it to an appropriate amount of hydrochloric acid aqueous solution to dissolve it, and then make up to 500 mL with hydrochloric acid aqueous solution of the same acidity to obtain a zirconium-hafnium mixed solution with a total metal ion concentration of about 0.5 mol / L.

[0043] 6.61 g of 18-crown-6 was added to the above zirconium-hafnium mixture to make the concentration of 18-crown-6 in the solution approximately 0.05 mol / L. After stirring until clear, the apparent pH was adjusted to 1.5 ± 0.05 with hydrochloric acid, and stirring was continued for 10 min to obtain the electrophoresis solution. ICP determination showed that the Zr:Hf mass ratio of this electrophoresis solution was 40.102:1, which was used as the subsequent calculation factor for the zirconium enrichment factor R. Zr Hafnium enrichment factor R Hf And the benchmark for the separation factor β at both ends.

[0044] The electrophoresis solution was added to a U-tube electrophoresis apparatus with an effective liquid volume of about 100 mL and an electrode spacing of 150 mm. Platinum sheet electrodes were used, and electrophoresis was performed at a constant voltage of 60 V for 10 min, corresponding to an average electric field strength of about 4.0 V / cm.

[0045] During electrophoresis, the temperature of the feed solution is controlled within the range of 15℃~35℃, preferably within the range of (25±3)℃, by a constant temperature water bath, and the temperature rise of a single electrophoresis is controlled to not exceed 5℃, so that only a small number of scattered bubbles are generated on the electrode surface, and no continuous bubble layer is formed; the liquid surface of the two arms of the U-shaped tube does not churn significantly, and no visible eddies or rapid back mixing of the liquid at both ends is observed.

[0046] After electrophoresis, immediately turn off the power and keep the U-tube electrophoresis apparatus vertical for about 60 seconds. Then use clamps to close the connection between the two arms of the U-tube and the bottom to prevent back mixing of liquids from the two sides during sampling.

[0047] In this embodiment, the position of the working surface of the effective electrode near the anode side in the U-tube electrophoresis device is taken as the sampling starting point of the anode end, and the position of the working surface of the effective electrode near the cathode side is taken as the sampling starting point of the cathode end; sampling is extended towards the middle region of the device along the electric field direction.

[0048] Specifically, in the U-tube electrophoresis apparatus with an electrode spacing of 150 mm described in this embodiment, the effective migration distance of 0-15% near the anode corresponds to the region of 0-22.5 mm on the anode side, i.e., the region of approximately 0-2.25 cm. In this embodiment, the liquid within the range of 0-2.0 cm near the anode is preferentially collected as the zirconium-enriched phase. This sampling range corresponds to approximately 0-13.3% of the effective migration distance, which is within the aforementioned 0-15% effective migration distance range. Correspondingly, the liquid within the range of 0-2.0 cm near the cathode is preferentially collected as the hafnium-enriched phase. The liquid between the two enriched regions is used as the intermediate region feed liquid, not as the target enriched product, and can be reused for front-end solution preparation or combined processing. During the liquid collection process, a segmented liquid collection tube or a pipette is used to slowly aspirate along the tube wall, without overall pouring or vigorous blowing.

[0049] In this embodiment, the collection ratio of the zirconium-enriched phase in the corresponding anode-side candidate collection region is 25%.

[0050] In this embodiment, the collection ratio of the candidate collection area on the anode side refers to the proportion of the volume of the candidate collection area on the anode side extending from the anode end along the electric field direction towards the middle of the device to the volume of the anode side region. In this embodiment, the anode side region refers to the liquid region that is separately separated near the anode end after electrophoresis is completed and the connection area between the two arms of the U-shaped tube and the bottom is clamped; the cathode side region is understood accordingly. The collection ratio is calculated based on the volume of the corresponding end region, rather than based on the total volume of the entire electrophoresis solution.

[0051] Whether the candidate collection region on the anode side is considered a zirconium-enriched phase should be determined based on its Zr:Hf mass ratio and zirconium enrichment factor R. Zr Make a judgment.

[0052] Before testing, dilute each sample to the instrument's linear range using a dilute acid system of the same acidity, and set up a reagent blank, matrix-matched standard curve, internal standard element, and at least three parallel determinations. For samples with turbidity or colloidal particles, the total Zr and total Hf contents should be measured after sufficient acidification and dissolution to avoid component bias caused by measuring only the supernatant.

[0053] The concentrations of Zr and Hf in the zirconium-enriched and hafnium-enriched phases were determined by ICP-MS or ICP-OES, and the zirconium enrichment factor R was calculated based on the Zr:Hf mass ratio of each feed solution. Zr Hafnium enrichment factor R Hf And the separation factor β at both ends.

[0054] In this embodiment, the Zr recovery rate is the local Zr recovery rate on the anode side, which refers to the proportion of the total Zr in the candidate collection area on the anode side to the total Zr in the anode side area after electrophoresis. This indicator is used to evaluate the impact of the collection ratio on the zirconium recovery amount and is not equivalent to the total Zr recovery rate in the entire electrophoresis solution.

[0055] The single-stage separation data for each feed liquid in this embodiment are shown in Table 1 below.

[0056] In Table 1 below, both Zr and Hf contents were determined using three parallel tests.

[0057] Table 1. Single-stage separation data for each feed liquid in this embodiment. As shown in Table 1, after adding 18-crown-6 and applying a DC electric field, the Zr:Hf near the anode region is higher than that of the electrophoretic feed solution, while the Zr:Hf near the cathode region is lower than that of the electrophoretic feed solution. The separation factor β at both ends is 1.180, indicating that the zirconium and hafnium species underwent measurable differential migration in this system.

[0058] Example 2 The similarities between this embodiment and Embodiment 1 will not be repeated here; only the differences from Embodiment 1 will be described. The difference between this embodiment and Embodiment 1 in the zirconium-hafnium separation method is that the apparent pH of the electrophoresis solution is adjusted to 1.0 and 2.0, respectively; the rest of the process is the same as in Embodiment 1, and zirconium-hafnium separation is performed accordingly.

[0059] The single-stage separation data for each feed liquid in this embodiment are shown in Table 2 below.

[0060] Table 2. Single-stage separation data for each feed liquid in this embodiment. As can be seen from Table 2 and the data in Example 1, within the apparent pH range of 1.0 to 2.0, the separation factor β at both ends is greater than 1.10, indicating that this acidity range can maintain the migratable charged species and exert the regulatory effect of 18-crown-6.

[0061] Example 3 The similarities between this embodiment and Embodiment 1 will not be repeated here; only the differences from Embodiment 1 will be described. The difference between this embodiment and Embodiment 1 in the zirconium-hafnium separation method is that zirconium-hafnium mixed solutions with total metal ion concentrations of 0.3 mol / L and 0.8 mol / L were prepared respectively; the remaining steps were the same as in Embodiment 1, and zirconium-hafnium separation was performed.

[0062] The single-stage separation data for each feed liquid in this embodiment are shown in Table 3 below.

[0063] Table 3. Single-stage separation data for each feed liquid in this embodiment. As shown in Table 3 and the data from Example 1, within the total metal ion concentration range of 0.3 mol / L to 0.8 mol / L, the Zr:Hf mass ratio of the zirconium-enriched phase is higher than that of the electrophoretic feed solution, while the Zr:Hf mass ratio of the hafnium-enriched phase is lower than that of the electrophoretic feed solution. The separation factors β at both ends are not lower than 1.10, indicating that acceptable zirconium-hafnium pre-enrichment effects can be achieved within this concentration range. Specifically, when the total metal ion concentration is 0.5 mol / L, the separation factors at both ends are relatively high, indicating better separation effect and operational stability.

[0064] Example 4 The similarities between this embodiment and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this embodiment and Example 1 lies in the adjustment of the 18-crown-6 concentration to 0.01 mol / L, 0.03 mol / L, 0.10 mol / L, and 0.20 mol / L; the remaining steps are the same as in Example 1, and zirconium-hafnium separation was performed.

[0065] The single-stage separation data for each feed liquid in this embodiment are shown in Table 4 below.

[0066] Table 4. Single-stage separation data for each feed liquid in this embodiment. As shown in Table 4 and the data from Example 1, under the conditions of apparent pH of electrophoresis solution = 1.5 ± 0.05, electric field strength of approximately 4.0 V / cm, and electrophoresis time of 10 min, when the concentration of 18-crown-6 is 0.01 mol / L to 0.20 mol / L, the separation factor β at both ends is 1.111 to 1.170, all not lower than 1.10, indicating that an acceptable pre-enrichment effect of zirconium and hafnium can be obtained within this concentration range. Specifically, when the concentration of 18-crown-6 is 0.03 mol / L to 0.10 mol / L, the separation factor β at both ends is 1.155 to 1.180, indicating a relatively better separation effect. When the concentration of 18-crown-6 is 0.01 mol / L or 0.20 mol / L, although some component differences can still be formed, the separation effect is lower than that in the 0.03 mol / L to 0.10 mol / L range.

[0067] Example 5 The similarities between this embodiment and Embodiment 1 will not be repeated here; only the differences from Embodiment 1 will be described. The difference between this embodiment and Embodiment 1 lies in the change of the type of crown ether complex auxiliary agent; the rest of the process is the same as in Embodiment 1, involving zirconium-hafnium separation.

[0068] In this embodiment, the concentration of each crown ether complex adjuvant is 0.05 mol / L, calculated as the molar concentration of the crown ether molecule or the crown ether skeleton. Specifically, 15-crown-5 is calculated as the molar concentration of the corresponding crown ether molecule; carboxyl-substituted 18-crown-6, sulfonic acid-substituted 18-crown-6, carboxyl-substituted dibenzo-18-crown-6, and sulfonic acid-substituted dibenzo-18-crown-6 are calculated as the molar concentration of their respective crown ether skeletons.

[0069] Table 5. Single-stage separation data for each feed liquid in this embodiment. As shown in Table 5 and the data from Example 1, 18-crown-6 exhibits a good separation-promoting effect in this system. 15-crown-5, carboxyl-substituted 18-crown-6, sulfonic acid-substituted 18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6, carboxyl-substituted dibenzo-18-crown-6, and sulfonic acid-substituted dibenzo-18-crown-6 all enable the separation factor β at both ends to reach or approach the acceptable pre-enrichment effect lower limit described in this invention, indicating that the above-mentioned crown ether complex additives can differentially regulate the electrophoretic migration behavior of zirconium and hafnium in acidic systems. Among them, 18-crown-6 has a higher separation factor β at both ends, making it a preferred crown ether complex additive in this zirconium-hafnium separation method.

[0070] Example 6 The similarities between this embodiment and Embodiment 1 will not be repeated here; only the differences from Embodiment 1 will be described. The difference between this embodiment and Embodiment 1 lies in the adjustment of the voltages to 20 V, 40 V, 80 V, and 100 V, corresponding to average electric field strengths of 1.33 V / cm, 2.67 V / cm, 5.33 V / cm, and 6.67 V / cm, respectively; the remaining steps are the same as in Embodiment 1, and zirconium-hafnium separation is performed accordingly.

[0071] The single-stage separation data for each feed liquid in this embodiment are shown in Table 6 below.

[0072] Table 6. Single-stage separation data for each feed liquid in this embodiment. As can be seen from Table 6 and the data in Example 1, the electric field strength affects the final zirconium-hafnium separation effect.

[0073] Specifically, within the electric field strength range of 1.33 V / cm to 6.67 V / cm, the separation factor β at both ends reaches 1.104 to 1.180.

[0074] Furthermore, when the electric field strength is controlled within the range of 2.67 V / cm to 5.33 V / cm, a superior separation efficiency is achieved compared to larger or smaller electric field strengths. The reason for this is that, under the U-tube apparatus and feed conditions of this embodiment, a lower electric field strength is not conducive to forming significant component differences; while a higher electric field strength may reduce the separation effect due to electrolytic bubbles, Joule heating, local convection, or diffusion mixing. Therefore, an appropriate electric field strength during electrophoresis is beneficial for effectively balancing the separation factors at both ends and operational stability.

[0075] In summary, considering both separation effect and operational stability, the present invention preferably controls the electric field strength within the range of 2.5 V / cm to 5.5 V / cm.

[0076] Example 7 The similarities between this embodiment and Embodiment 1 will not be repeated here; only the differences from Embodiment 1 will be described. The difference between this embodiment and Embodiment 1 in the zirconium-hafnium separation method is that the electrophoresis time is adjusted to 5 min, 12 min, and 15 min respectively; the rest of the process is the same as in Embodiment 1, and zirconium-hafnium separation is performed accordingly.

[0077] The single-stage separation data for each feed liquid in this embodiment are shown in Table 7 below.

[0078] Table 7. Single-stage separation data for each feed liquid in this embodiment. As can be seen from Table 7 and the data in Example 1, the separation factor β at both ends is 1.130 to 1.172 within the electrophoresis time range of 5 min to 15 min, indicating that a better difference between the two components can be formed within this time range.

[0079] Example 8 This embodiment is used to determine the sampling boundary of the zirconium-enriched phase in a U-tube electrophoresis apparatus.

[0080] The similarities between this embodiment and Embodiment 1 will not be repeated here; only the differences from Embodiment 1 will be described. The difference between this embodiment and Embodiment 1 in the zirconium-hafnium separation method lies in the detection of the Zr:Hf mass ratio of the liquid within a 0-1 cm range near the anode, and the calculation of R. Zr Among them, 0~1 cm corresponds to approximately 0~6.7% of the effective migration distance.

[0081] The Zr:Hf variation at different sampling ranges on the anode side in this embodiment is shown in Table 8 below.

[0082] Table 8. Variation of Zr:Hf at different sampling ranges on the anode side. As can be seen from Table 8 and the data in Example 1, in the U-tube electrophoresis apparatus with an electrode spacing of 150 mm described in this example, zirconium enrichment is observed in both the 0-1 cm and 0-2 cm ranges near the anode, corresponding to 0-6.7% and 0-13.3% of the effective migration distance, respectively. Therefore, the 0-2 cm range near the anode corresponds to approximately 0-13.3% of the effective migration distance, falling within the 0-15% effective migration distance range, and can be considered as the collection area for the zirconium-enriched phase in this example.

[0083] Example 9 This embodiment is used to investigate the effect of the collection ratio of the candidate collection region on the anode side on the zirconium enrichment factor and the local Zr recovery rate on the anode side.

[0084] It should be noted that this embodiment is not intended to prove whether electrophoretic separation occurs, but rather to further determine the volume boundary when the zirconium-enriched phase is actually collected after the zirconium-enriched region on the anode side is formed under the conditions described in Example 1.

[0085] The zirconium-hafnium separation method provided in this embodiment differs from that in Embodiment 1 in that the collection ratio of the candidate collection area on the anode side is adjusted to 10%, 20%, and 30%, respectively; the rest is as shown in Embodiment 1, and zirconium-hafnium separation is performed.

[0086] The effect of the collection ratio of the candidate collection area on the anode side on the zirconium enrichment factor and the local Zr recovery rate on the anode side in this embodiment is shown in Table 9 below.

[0087] Table 9. Effect of the collection ratio in the candidate collection area on the anode side on the zircon enrichment factor and local Zr recovery on the anode side. As can be seen from Table 9 and the data in Example 1, as the collection ratio of the candidate collection region on the anode side increased from 10% to 30%, the local Zr recovery rate on the anode side increased from 31% to 75%, while R Zr The value gradually decreased from 1.085 to 1.040. This indicates that increasing the collection ratio is beneficial for improving the local Zr recovery on the anode side, but it will reduce the average Zr:Hf mass ratio of the collected liquid. Considering both the zirconium enrichment factor and the local Zr recovery rate on the anode side, the collection ratio of the candidate collection area on the anode side in this zirconium-hafnium separation method is controlled at 10%~30%, preferably 20%~25%.

[0088] To demonstrate the influence of various parameters on the separation effect in the zirconium-hafnium separation method of the present invention, several comparative experiments were conducted.

[0089] Comparative Example 1 The similarities between this comparative example and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this comparative example and Example 1 in the zirconium-hafnium separation method is that the apparent pH of the electrophoresis solution is adjusted to 0.5 and 3.0, respectively; the rest of the zirconium-hafnium separation is performed as described in Example 1.

[0090] The single-stage separation data for each feed liquid in this comparative example are shown in Table 10 below.

[0091] Table 10 Single-stage separation data for each feed liquid in this comparative example. Comparing Example 1, Example 2 and this comparative example, it can be seen that when the apparent pH is 0.5 or 3.0, the separation factor β at both ends is less than 1.10, and the separation effect decreases. This indicates that when the acidity deviates from the range of 1.0 to 2.0, the hydrolysis and polymerization, complexation state or colloidal stability of zirconium and hafnium species change, which is not conducive to the formation of stable electrophoretic migration differences.

[0092] Comparative Example 2 The similarities between this comparative example and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this comparative example and Example 1 lies in the adjustment of the 18-crown-6 concentration to 0 and 0.005 mol / L, respectively; the remaining steps are the same as in Example 1, and zirconium-hafnium separation was performed.

[0093] The single-stage separation data for each feed liquid in this comparative example are shown in Table 11 below.

[0094] Table 11 Single-stage separation data for each feed liquid in this comparative example. By comparing Examples 1, 4, and this comparative example, it can be seen that without the addition of 18-crown-6, the separation factor β at both ends is 1.020, close to 1, indicating that the difference between zirconium and hafnium components is small under simple electrophoretic conditions. When the concentration of 18-crown-6 is 0.005 mol / L, β increases to 1.085, indicating that the low concentration of crown ether auxiliaries has begun to regulate the apparent electrophoretic migration behavior of zirconium and hafnium, but the separation effect is still lower than the acceptable pre-enrichment effect limit of this invention. When the concentration of 18-crown-6 is 0.01 mol / L, β reaches 1.111, which can be considered to be the lower limit of acceptable pre-enrichment effect; when the concentration of 18-crown-6 is 0.03 mol / L to 0.10 mol / L, β is 1.155 to 1.180, and the separation effect is good; when the concentration of 18-crown-6 is increased to 0.20 mol / L, β is 1.117, which still has a certain pre-enrichment effect, but it is lower than that in the 0.03 mol / L to 0.10 mol / L range.

[0095] It is evident that the appropriate concentration of the complexing agent used to induce differentiated electrophoretic behavior in zirconium and hafnium is beneficial to expanding the differentiation of the formed migratory charged species under the influence of an electric field.

[0096] Comparative Example 3 The similarities between this comparative example and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this comparative example and Example 1 in the zirconium-hafnium separation method is that the type of crown ether complex auxiliary agent is changed to 12-crown-4; the rest of the process is the same as in Example 1, and zirconium-hafnium separation is performed accordingly.

[0097] The single-stage separation data for each feed liquid in this comparative example are shown in Table 12 below.

[0098] Table 12 Single-stage separation data for each feed liquid in this comparative example. As can be seen from Table 12, when 12-crown-4 is used as an auxiliary agent for crown ether complexes, the separation factor β at both ends is 1.070, which is lower than the acceptable pre-enrichment effect lower limit of β not less than 1.10 as described in this invention. This indicates that 12-crown-4 is insufficient to amplify the apparent electrophoretic migration difference between zirconium and hafnium under the conditions of this embodiment, and cannot be used as an auxiliary agent for crown ether complexes of this invention.

[0099] The possible reason for this is that the regulation of the electrophoretic migration behavior of zirconium and hafnium species by crown ether complex auxiliaries is related to the ring cavity size, spatial arrangement of ether oxygen sites, and their ability to influence hydrolyzed polymers, complexes, or ion-associated compounds. The 12-crown-4 has a smaller ring cavity size and a different spatial arrangement of ether oxygen sites compared to the 18-crown-6, resulting in a weaker regulatory effect on the solvation layer, ion association state, or apparent charge density of zirconium and hafnium-related charged species in acidic aqueous phases. Therefore, it is difficult to achieve a β value of at least 1.10 between the two components.

[0100] Comparative Example 4 The similarities between this comparative example and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this comparative example and Example 1 in the zirconium-hafnium separation method is that the electrophoresis time is shortened to 3 minutes; the rest of the process is the same as in Example 1, with zirconium-hafnium separation performed accordingly.

[0101] The single-stage separation data for each feed liquid in this comparative example are shown in Table 13 below.

[0102] Table 13 Single-stage separation data for each feed liquid in this comparative example. By comparing the single-stage separation data of Examples 1, 7 and this comparative example under different electrophoresis times, it can be seen that the electrophoresis time has a significant impact on the final zirconium-hafnium separation effect.

[0103] Specifically, when the electrophoresis time was between 5 and 15 minutes, the enrichment factors of zirconium and hafnium were between 1.033 and 1.050 and 1.103 and 1.116, respectively, and the separation factor β at both ends reached at least 1.130, indicating a relatively good separation level. However, when the electrophoresis time was shortened to 3 minutes, β dropped to 1.093, which was lower than the acceptable pre-enrichment effect limit of this invention, indicating that the migration differences had not yet been fully formed.

[0104] Furthermore, when the electrophoresis time was extended to 15 min, β was 1.130. Although some component differences still existed, it was lower than the 1.155-1.172 range of 5 min to 12 min, which is presumably related to diffusion mixing, bubble disturbance, or Joule heating. Therefore, the present invention preferably controls the electrophoresis time to 5 min to 12 min.

[0105] Analysis revealed that, under the U-tube apparatus and feed conditions of these embodiments and comparative examples, excessively short electrophoresis times were not conducive to forming significant component differences; while excessively long electrophoresis times could reduce the separation effect due to electrolytic bubbles, Joule heating, local convection, or diffusion mixing.

[0106] It is evident that an appropriate electrophoresis duration is beneficial for effectively balancing the separation factors at both ends and operational stability.

[0107] Comparative Example 5 The similarities between this comparative example and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this comparative example and Example 1 in the zirconium-hafnium separation method is that, after electrophoresis, samples are taken from the anode side towards the central region to detect the Zr:Hf mass ratio of the liquid within 2 cm to 3 cm and 3 cm to 4 cm of the liquid closest to the anode, and R is calculated. Zr .

[0108] The Zr:Hf variation at different sampling ranges on the anode side of this comparative example is shown in Table 14 below.

[0109] Table 14. Variation of Zr:Hf at different sampling ranges on the anode side Combining Examples 1 and 8 with this comparative example, it can be seen that in the U-tube electrophoresis apparatus with an electrode spacing of 150 mm, when the sampling range extends to 2 cm to 3 cm on the anode side, this range corresponds to approximately 13.3% to 20.0% of the effective migration distance near the anode end. Zr When the concentration drops to 1.023, it is close to the electrophoretic feed level and is not suitable as a preferred zirconium-enriched phase. When the sampling range is further extended to 3 cm to 4 cm on the anode side, this range corresponds to approximately 20.0% to 26.7% of the effective migration distance near the anode end. Zr The value is 1.006, which is basically in the middle region of the liquid. Therefore, in the U-tube electrophoresis apparatus described in Examples 1, 8 and this comparative example, the effective migration distance range of 0 to 15% near the anode can be used as the collection area for the zirconium-enriched phase, and the liquid from about 15% near the anode to the middle region is not used as the target enriched product, but can be reused or combined as the middle region liquid.

[0110] Comparative Example 6 The similarities between this comparative example and Example 1 will not be repeated here; only the differences from Example 1 will be described. The difference between this comparative example and Example 1 lies in that the collection ratio of the candidate collection region on the anode side is increased to 40% to examine the effect of an excessively large collection ratio on the zirconium enrichment factor R. Zr The influence of local Zr recovery rate on the anode side was investigated; for the remainder, zirconium-hafnium separation was performed as shown in Example 1.

[0111] The effects of the collection ratio in the candidate collection area on the anode side of this comparative example on the zirconium enrichment factor and the local Zr recovery on the anode side are shown in Table 15 below.

[0112] Table 15. Effect of the collection ratio in the candidate collection area on the anode side on the zircon enrichment factor and local Zr recovery on the anode side. By comparing Examples 1, 9, and this comparative example, it can be seen that as the collection ratio of the candidate collection area on the anode side increases, the local Zr recovery rate on the anode side improves, but the zirconium enrichment factor R... Zr Decrease. When the collection rate is 10%~30%, R Zr The value was 1.040~1.085, indicating that the Zr:Hf mass ratio of the collected liquid in the candidate region on the anode side was still higher than that of the electrophoretic feed solution, and it could be used as a zirconium-enriched phase; when the collection ratio was increased to 40%, R Zr The enrichment effect decreased significantly to 1.018. This is because, as the collection ratio increases, the collection range at the anode end gradually extends towards the middle of the device. The proportion of liquid with lower enrichment levels at the anode side distal to the anode or the transition liquid near the middle region increases, thereby reducing the average Zr:Hf mass ratio of the collected liquid. Therefore, in the electrophoresis apparatus described in this zirconium-hafnium separation method, it is preferable to collect 10% to 30% of the zirconium-enriched phase from the anode side region, more preferably 20% to 25%, to balance the zirconium enrichment factor and the local Zr recovery rate on the anode side.

[0113] The above embodiments are only used to illustrate specific implementations of the present invention and do not constitute a limitation on the scope of protection of the present invention. Equivalent substitutions made by those skilled in the art, within the range of process parameters and separation effect requirements disclosed in the present invention, regarding the device type, liquid collection method, or crown ether additive form, should all be understood as falling within the scope of protection of the present invention.

Claims

1. A method for separating zirconium and hafnium based on the regulation of electrophoretic migration behavior using crown ether complex auxiliaries, characterized in that, Including the following steps: S1. Dissolve the raw materials containing zirconium and hafnium in an acidic medium to prepare a zirconium-hafnium mixed solution; wherein the total metal ion concentration of the zirconium-hafnium mixed solution is 0.3 mol / L~0.8 mol / L, expressed as the total molar concentration of Zr and Hf; S2. Add crown ether complex additives to the zirconium-hafnium mixture and adjust the apparent pH of the obtained mixture to 1.0~2.0 to obtain an electrophoretic feed solution containing zirconium species and hafnium species; The concentration of the crown ether complex auxiliaries in the electrophoresis solution is 0.01 mol / L to 0.20 mol / L, based on the molar concentration of the crown ether molecules; the crown ether complex auxiliaries are selected from 15-crown-5, 18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6, and one or more of the hydroxyl, carboxyl, sulfonic acid, amide, phosphoxy, or polyether chain substituted derivatives of the above crown ethers. S3. The electrophoretic solution is introduced into the electrophoresis apparatus and electrophoresed for 5 min to 15 min under a DC electric field strength of 1.3 V / cm to 6.7 V / cm, so that the zirconium species and the hafnium species undergo differential migration in the electric field; S4. After electrophoresis, turn off the power and keep the electrophoresis apparatus stationary. Then, collect the liquid in segments along the direction of the electric field, collecting the zirconium-enriched phase near the anode and the hafnium-enriched phase near the cathode. The zirconium-enriched phase refers to the liquid near the anode where the Zr:Hf mass ratio is higher than the corresponding Zr:Hf mass ratio in the electrophoresis feed solution. The hafnium-enriched phase refers to the liquid near the cathode where the Zr:Hf mass ratio is lower than the corresponding Zr:Hf mass ratio in the electrophoresis feed solution. The separation factor β between the two ends of the zirconium-enriched phase and the hafnium-enriched phase collected in pairs is not less than 1.

10.

2. The zirconium-hafnium separation method according to claim 1, characterized in that, In step S1, the total metal ion concentration of the zirconium-hafnium mixture is 0.4 mol / L to 0.6 mol / L.

3. The zirconium-hafnium separation method according to claim 1, characterized in that, In step S2, the concentration of the crown ether complex auxiliaries in the electrophoresis solution is 0.03 mol / L to 0.10 mol / L.

4. The zirconium-hafnium separation method according to claim 3, characterized in that, In step S2, the concentration of the crown ether complex auxiliaries in the electrophoresis solution is 0.05 mol / L to 0.10 mol / L.

5. The zirconium-hafnium separation method according to any one of claims 1, 3, or 4, characterized in that, In step S2, the crown ether complex adjuvant is selected from one or more of 18-crown-6, carboxyl-substituted 18-crown-6, sulfonic acid-substituted 18-crown-6, water-soluble substituted derivatives of benzo-18-crown-6, and water-soluble substituted derivatives of dibenzo-18-crown-6.

6. The zirconium-hafnium separation method according to claim 1, characterized in that, In step S3, the DC electric field strength is 2.5 V / cm to 5.5 V / cm.

7. The zirconium-hafnium separation method according to claim 1 or 6, characterized in that, In step S3, the electrophoresis device is selected from any one of the following: U-tube electrophoresis device, horizontal tank electrophoresis device, flat plate flow channel electrophoresis device, and diaphragm electrophoresis tank electrophoresis device.

8. The zirconium-hafnium separation method according to claim 7, characterized in that, In step S4, the zirconium-enriched phase is taken from the liquid within 0-15% of the effective migration distance near the anode, and the hafnium-enriched phase is taken from the liquid within 0-15% of the effective migration distance near the cathode.

9. The zirconium-hafnium separation method according to claim 8, characterized in that, In step S4, the zirconium-enriched phase is collected in segments from the anode-side region, and its collection volume accounts for 10% to 30% of the volume of the anode-side region; the hafnium-enriched phase is collected in segments from the cathode-side region according to the corresponding proportion, and its collection volume accounts for 10% to 30% of the volume of the cathode-side region.

10. The zirconium-hafnium separation method according to claim 9, characterized in that, In step S4, the collection volume of the zirconium-enriched phase accounts for 20% to 25% of the volume of the anode-side region; the collection volume of the hafnium-enriched phase accounts for 20% to 25% of the volume of the cathode-side region.

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