An electrochemical method for zirconium-hafnium separation

Abstract

This invention provides an electrochemical method for separating zirconium and hafnium, employing an electrolytic cell with an anode chamber and a cathode chamber separated by a liquid alloy. Specifically, the liquid alloy comprises crude zirconium and a molten metal with lower metallic activity than zirconium. After the electrolysis reaction begins, due to the order of metallic activity in the liquid alloy: hafnium > zirconium >> molten metal, hafnium in the liquid alloy is preferentially oxidized before zirconium. Hafnium enters the electrolyte in the cathode chamber in ionic form, causing the hafnium content in the liquid alloy to continuously decrease, while zirconium remains in the liquid alloy. This achieves deep separation of zirconium and hafnium, enabling the preparation of nuclear-grade zirconium products.

Description

Technical Field

[0001] This invention relates to the field of zirconium metallurgy, and more specifically to an electrochemical method for separating zirconium and hafnium. Background Technology

[0002] Zirconium and hafnium both belong to the category of high-melting-point rare metals and are widely used in aerospace, nuclear energy, metallurgy, chemical industry, and medical fields. Hafnium has a large thermal neutron capture cross section of 115 Å, while zirconium's is only 0.18 Å. Therefore, the zirconium cladding used in uranium nuclear fuel requires hafnium levels to be reduced to extremely low levels (100 ppm). However, because zirconium and hafnium both belong to Group IV transition metals, their atomic and ionic radii and structures are very similar, and their chemical properties are also very similar. Therefore, zirconium and hafnium often occur together in nature (hafnium accounts for about 1-2% of the total mass of zirconium and hafnium), and separation during smelting is difficult. With the transformation of the world's energy structure, the demand for nuclear-grade zirconium in the nuclear industry is constantly increasing, making the development of new zirconium-hafnium separation processes of great significance.

[0003] Since the mid-20th century, developed countries have conducted extensive research on the separation of zirconium and hafnium, primarily employing methods such as solvent extraction, fractional crystallization, and molten salt extraction. Solvent extraction, in particular, is mainly used for ZrO in aqueous solutions. 2+ With HfO 2+ Differences in properties, such as with SCN - For different coordination abilities, methyl isobutyl ketone (MIBK) is used for extraction and separation; for different phosphorus-oxygen coordination abilities, tributyl phosphate (TBP) is used for extraction and separation, as well as N235 extraction. However, due to problems such as water loss and volatilization of organic extractants, these methods still need continuous improvement. Stepwise crystallization utilizes the difference in solubility of zirconium and hafnium compounds for separation. For example, the solubility of K2HfF6 is twice that of K2ZrF6, and the water solubility properties of zirconium-hafnium phosphate and ferricyanide compounds are significantly different. However, this type of method only appeared in early research due to its low efficiency. In addition, the distillation method that uses the difference in molecular weight of ZrCl4 and HfCl4 for separation has the disadvantages of high temperature and high energy consumption.

[0004] Since the 1970s, Megy et al. developed a molten salt extraction method based on the differences in redox properties of zirconium, hafnium, and their halides between molten salt and metal. The basic principle is that hafnium in a high-temperature liquid alloy (zinc-zirconium-hafnium) reacts with zirconium ions in the molten salt. Zirconium remains in the liquid alloy, while hafnium enters the molten salt, thus achieving the separation of zirconium and hafnium. Building on this, researchers at Delft University of Technology in the Netherlands mixed zirconium and hafnium with copper-tin to form a liquid alloy. Utilizing the stronger reducing power of hafnium than zirconium, hafnium preferentially reduces copper ions in the molten salt, allowing it to enter the molten salt. This causes hafnium in the liquid metal to be oxidized and enter the molten salt, while copper ions in the molten salt are reduced and enter the liquid alloy. Zirconium, relatively speaking, remains in the liquid alloy, thus achieving hafnium removal. However, the addition of copper ions not only oxidizes hafnium but also oxidizes a large amount of zirconium, making it difficult to control the oxidation rate of zirconium and hafnium in the liquid alloy. Therefore, although the separation coefficient of zirconium and hafnium reaches about 600 in actual experimental studies, zirconium is lost due to the oxidation of copper ions during the reaction process. When 99.5% of hafnium is removed, the loss of zirconium is as high as 44%.

[0005] In summary, given the problems with existing technologies, there is a need to develop efficient zirconium-hafnium separation technology. Summary of the Invention

[0006] This invention provides an electrochemical method for zirconium-hafnium separation. By controlling the oxidation rate electrochemically, hafnium in the liquid alloy is slowly oxidized, reducing zirconium loss and achieving deep separation of zirconium and hafnium. The method includes:

[0007] An electrolytic cell with an anode chamber and a cathode chamber is used. An anode electrolyte and a cathode electrolyte are respectively provided in the anode chamber and the cathode chamber. The anode electrode is inserted into the anode electrolyte and the cathode electrode is inserted into the cathode electrolyte. The anode chamber and the cathode chamber are separated by a liquid alloy, and neither the anode nor the cathode electrode comes into contact with the liquid alloy.

[0008] The liquid alloy comprises a solute metal and a molten metal. The solute metal is crude zirconium. Since zirconium and hafnium often coexist in nature, the crude zirconium contains some hafnium. Further, the mass percentage of hafnium in the crude zirconium is ≤5%, preferably 1-2%. The molten metal has lower metallic activity than zirconium.

[0009] After the electrolysis reaction begins, since the order of metal activity in the liquid alloy is: hafnium > zirconium >> molten metal, hafnium in the liquid alloy is preferentially oxidized before zirconium. Hafnium enters the cathode electrolyte in ionic form, causing the hafnium content in the liquid alloy to decrease continuously, while zirconium remains in the liquid alloy, thus achieving the separation of zirconium and hafnium.

[0010] Furthermore, the anode electrode material is selected from graphite, copper, and crude zirconium. The hafnium content in the crude zirconium is the same as that in the crude zirconium used as a solute metal.

[0011] Furthermore, when the anode electrode is made of graphite, a zirconium-containing material needs to be added to the anode chamber. This zirconium-containing material is a zirconium halide or oxide, preferably selected from one or more of Na₂ZrCl₆, K₂ZrCl₆, Na₂ZrF₆, K₂ZrF₆, ZrO₂, ZrCl₂, ZrCl₃, and ZrCl₄. Furthermore, when the anode electrode is made of copper or crude zirconium, it is not necessary to add a zirconium-containing material to the anode chamber.

[0012] Furthermore, the molten metal is selected from one or more of copper, lead, zinc, tin, and bismuth, and the solute metal and molten metal form a liquid alloy with a melting point below 1100℃. The selection principle for each component and its proportion in the liquid alloy is as follows: first, determine the operating temperature of the electrolytic cell, and then determine the metal composition in the liquid alloy. Based on the alloy phase diagram of zirconium and the molten metal, determine the ratio of their amounts to ensure that the selected alloy components are in a molten state at that temperature.

[0013] When the anode electrode material is copper, the anode electrolyte is selected from one or more of CuCl2 and LiF, NaF, KF, LiCl, NaCl, KCl, and CaCl2. When the anode electrode material is graphite or zirconium, the anode electrolyte is selected from one or more of ZrCl4, ZrCl2, ZrCl3, Na2ZrF6, and K2ZrF6 and one or more of LiF, NaF, KF, LiCl, NaCl, KCl, and CaCl2. The cathode electrolyte is selected from one or more of LiF, NaF, KF, LiCl, NaCl, KCl, and CuCl2, and contains dissolved zirconium and / or hafnium halides. The zirconium and / or hafnium halides are selected from one or more of ZrCl4, ZrCl2, ZrCl3, HfCl4, HfCl2, HfCl3, Na2ZrCl6, K2ZrCl6, Na2HfCl6, K2HfCl6, Na2ZrF6, K2ZrF6, Na2HfF6, and K2HfF6. There are no specific requirements for the ratio of zirconium and / or hafnium halides to other molten salts. In principle, it is sufficient to ensure that the cathode and anode electrolytes are in a molten state at the electrolytic cell's operating temperature, and that the density of the electrolytes is lower than the density of the liquid alloy, ensuring that the liquid electrolyte floats on the surface of the liquid alloy.

[0014] Furthermore, the cathode electrode is made of stainless steel, zirconium, titanium, or tungsten.

[0015] Furthermore, the electrolysis reaction is carried out under argon protection at a temperature of 400–1100 °C, and an electric field is applied between the anode and cathode, controlling the current density to be 0.002–0.5 A·cm⁻¹. -2 .

[0016] When the anode electrode is made of graphite, zirconium-containing material, i.e., zirconium halide or oxide, needs to be added to the anode chamber through the zirconium-containing material inlet. The reaction process is as follows: Inert gas is introduced into the tank through the gas inlet, and the tank is heated by a resistance wire to initiate the electrolysis reaction. The zirconium-containing material added to the anode chamber gains electrons at the interface between the anode electrolyte and the liquid alloy and is reduced to metallic zirconium, which dissolves in the liquid alloy. Simultaneously, since the reactivity order of the metals in the liquid alloy is: hafnium > zirconium >> molten metal, and the liquid alloy loses electrons during the above anode reaction, hafnium preferentially undergoes electron-loss oxidation with zirconium and molten metal, generating hafnium ions that enter the cathode electrolyte. In the above electrolysis reaction, hafnium in the liquid alloy is continuously converted into hafnium ions and enters the cathode electrolyte, while zirconium remains in the liquid alloy, achieving zirconium-hafnium separation.

[0017] When the anode electrode is made of copper or crude zirconium, it is not necessary to add zirconium-containing materials into the anode chamber. Specifically:

[0018] When the anode electrode is made of molten copper, the electrolysis process is as follows: The electrolytic cell operates under inert gas protection. The anode electrode undergoes an oxidation reaction, losing electrons. The copper, acting as the anode electrode, is oxidized and enters the anode electrolyte as a cation. At the interface between the anode electrolyte and the liquid alloy, it is reduced to elemental copper, which then enters the liquid alloy as a molten metal component. Based on the metal activity order of hafnium > zirconium >> molten metal, hafnium in the liquid alloy is preferentially oxidized before zirconium, entering the cathode electrolyte as an ion. During this process, because hafnium is preferentially oxidized and enters the cathode electrolyte, the hafnium content in the liquid alloy continuously decreases, thus achieving the separation of zirconium and hafnium.

[0019] When the anode electrode is made of crude zirconium, the electrolysis process is as follows: The electrolytic cell operates under inert gas protection. The anode electrode undergoes an oxidation reaction and loses electrons. The crude zirconium, serving as the anode electrode, is oxidized, and zirconium enters the anode electrolyte as a cation. At the interface between the anode electrolyte and the liquid alloy, it is reduced to elemental zirconium, which then enters the liquid alloy. During this process, due to the metal activity order in the liquid alloy being: hafnium > zirconium, zirconium is preferentially reduced into the liquid alloy before hafnium, while hafnium remains in the anode electrolyte. Based on this metal activity order, hafnium in the liquid alloy is preferentially oxidized before zirconium, and hafnium enters the cathode electrolyte in ionic form. In this process, because hafnium is preferentially oxidized into the cathode electrolyte before zirconium, the hafnium content in the liquid alloy continuously decreases, thus achieving the separation of zirconium and hafnium.

[0020] In the aforementioned electrolysis process, when the anode electrode is made of graphite and zirconium, zirconium continuously enters the liquid alloy from the electrolyte in the anode chamber, while hafnium from the liquid alloy continuously enters the electrolyte in the cathode chamber, achieving zirconium-hafnium separation. When the anode electrode is made of copper, copper continuously enters the liquid alloy from the electrolyte in the anode chamber, while hafnium from the liquid alloy continuously enters the electrolyte in the cathode chamber, achieving zirconium-hafnium separation. Furthermore, the liquid alloy can be directly used as the anode for electrolysis to separate hafnium from the liquid alloy.

[0021] The beneficial effects of this invention are:

[0022] This invention provides an electrochemical method for separating zirconium and hafnium, employing an electrolytic cell with an anode chamber and a cathode chamber separated by a liquid alloy. Specifically, the liquid alloy comprises crude zirconium and a molten metal with lower metallic activity than zirconium. After the electrolysis reaction begins, due to the order of metallic activity in the liquid alloy: hafnium > zirconium >> molten metal, hafnium in the liquid alloy is preferentially oxidized before zirconium. Hafnium enters the cathode electrolyte in ionic form, causing the hafnium content in the liquid alloy to continuously decrease, while zirconium remains in the liquid alloy. This achieves deep separation of zirconium and hafnium, enabling the preparation of nuclear-grade zirconium products. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the electrolytic cell of the present invention.

[0024] Wherein, 1-anode electrode; 2-anode chamber; 3-liquid alloy; 4-cathode chamber; 5-cathode electrode; 6-tank body; 7-resistance wire; 8-air inlet; 9-air outlet; 10-zirconium-containing material inlet; 11-liquid alloy inlet. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] This invention relates to an electrochemical method for separating zirconium and hafnium, the method being carried out in an electrolytic cell. For example... Figure 1 As shown, the main body of the electrolytic cell used in this invention is a tank body 6, which has an anode chamber 2 and a cathode chamber 4. An anode electrolyte and an anode electrode 1 are provided in the anode chamber 2, and a cathode electrolyte and a cathode electrode 5 are provided in the cathode chamber 4. The anode chamber 2 and the cathode chamber 4 are separated by a liquid alloy 3. Figure 1Liquid alloy 3 is contained in the connected area below the tank body 6, and an anode chamber 2 and a cathode chamber 4 are respectively provided above the tank body 6. The interface formed by the liquid alloy 3 and the electrolyte defines the areas of the anode chamber 2 and the cathode chamber 4, and neither the cathode electrode 5 nor the anode electrode 1 is in contact with the liquid alloy 3.

[0027] The tank 6 is a completely enclosed structure. An inlet 8 for inert gas entry and an outlet 9 for exhausting gas from the tank 6 are located at the top of the tank 6. A zirconium-containing material inlet 10 is located above the anode chamber, and a liquid alloy inlet 11 is located between the anode chamber 2 and the cathode chamber 4. A heating resistance wire 7 is provided on the outer surface of the tank 6.

[0028] After electrolysis for a certain period, the liquid alloy can be directly electrolytically separated from the solute metal zirconium and the molten metal to extract zirconium; alternatively, the reaction system can be cooled, the metal phase separated from the electrolyte, and then the liquid alloy extracted. Zirconium extraction from liquid alloys can employ general metallurgical separation methods (such as molten salt electrolytic oxidation separation of zirconium from liquid alloys). The final zirconium product obtained contains less than 100 ppm of hafnium, meeting the requirements for hafnium in nuclear-grade zirconium products.

[0029] Example 1

[0030] Electrolysis reaction in such Figure 1 The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 1:1, and 10g of zirconium powder (containing 2.2% hafnium by mass) was added as the solute metal. A graphite rod was used as the anode electrode, stainless steel as the cathode electrode, and refractory ceramic as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of NaCl, KCl, and ZrCl3 was prepared as the cathode electrolyte in the cathode chamber at a mass ratio of 1:1:0.02. Under an argon atmosphere, the mixture was heated to 800℃ at a rate of 10℃ / min and held for 1 hour. Potassium fluorozirconate (containing 2.2% hafnium by mass) was added to the anode chamber while a voltage was applied, controlling the current density to be 0.02 A·cm⁻¹. -2 Zirconium ions in the anode electrolyte are continuously reduced and enter the liquid alloy, while hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After electrolysis for 6 hours, a sample is taken from the liquid alloy feed port.

[0031] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.007% of the total mass of zirconium and hafnium, meeting the requirements for hafnium content in nuclear-grade zirconium.

[0032] Example 2

[0033] 500g of molten metal was prepared according to a copper-tin ratio of 1:1, and 10g of zirconium powder (of which hafnium accounted for 2.2% of the total mass of zirconium and hafnium) was added as the solute metal. The liquid alloy was directly connected as the anode, zirconium as the cathode, and refractory ceramic as the tank lining. 300g of cathode electrolyte was prepared by adding NaCl and K₂ZrF₆ in a mass ratio of 1:0.02 to the cathode chamber. Under an argon atmosphere, the mixture was heated to 900℃ at a rate of 10℃ / min, with the current density controlled at 0.02 A·cm⁻¹. -2 After electrolysis for 1 hour, the liquid alloy is removed.

[0034] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.009% of the total mass of zirconium and hafnium, meeting the requirements for hafnium content in nuclear-grade zirconium.

[0035] Example 3

[0036] 500g of molten metal was prepared according to a copper-tin ratio of 1:1, and 10g of zirconium powder (of which hafnium accounted for 2.2% of the total mass of zirconium and hafnium) was added as the solute metal. A copper rod was used as the anode electrode, stainless steel as the cathode electrode, and refractory ceramic as the tank lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of cathode electrolyte was prepared in the cathode chamber using NaCl, KCl, and ZrCl2 in a mass ratio of 1:1:0.02. Under an argon atmosphere, the mixture was heated to 900℃ at a rate of 10℃ / min and held for 1 hour. A voltage was applied, and the current density was controlled at 0.015 A·cm⁻¹. -2 During the electrolysis process, the copper anode is continuously oxidized and enters the anode electrolyte in the form of copper ions. It is then reduced on the surface of the liquid alloy and enters the liquid alloy. At the same time, the hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After 6 hours of electrolysis, a sample is taken from the liquid alloy feed port.

[0037] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.005% of the total mass of zirconium and hafnium, meeting the requirements for hafnium content in nuclear-grade zirconium.

[0038] Example 4

[0039] Electrolysis reaction in such Figure 1The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 1:1, and 10g of zirconium powder (containing 2.2% hafnium by mass) was added as the solute metal. Zirconium was used as the anode electrode (containing 2.2% hafnium by mass), stainless steel as the cathode electrode, and refractory ceramic as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of cathode electrolyte was prepared in the cathode chamber using NaCl, KCl, and ZrCl2 at a mass ratio of 1:1:0.02. Under an argon atmosphere, the mixture was heated to 900℃ at a rate of 10℃ / min and held for 1 hour. A voltage was then applied, and the current density was controlled at 0.02 A·cm⁻¹. -2 The zirconium ions in the anode electrolyte are continuously reduced and enter the liquid alloy, while the hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After electrolysis for 6 hours, a sample is taken from the liquid alloy feed port.

[0040] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.007% of the total mass of zirconium and hafnium, meeting the requirements for hafnium content in nuclear-grade zirconium.

[0041] Example 5

[0042] Electrolysis reaction in such Figure 1 The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 1:1, and 10g of zirconium powder (containing 2.2% hafnium by mass) was added as the solute metal. A graphite rod was used as the anode electrode, stainless steel as the cathode electrode, and refractory ceramic as the cell lining. 300g of NaCl-KCl-NaF electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1:0.1. 300g of NaCl, KCl, and ZrCl3 were added to the cathode chamber to prepare a cathode electrolyte in a mass ratio of 1:1:0.1. Under an argon atmosphere, the mixture was heated to 900℃ at a rate of 10℃ / min and held for 1 hour. Potassium fluorozirconate (containing 2.2% hafnium by mass) was added to the anode chamber while a voltage was applied, controlling the current density to be 0.02 A·cm⁻¹. -2 Zirconium ions in the anode electrolyte are continuously reduced and enter the liquid alloy, while hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After electrolysis for 6 hours, a sample is taken from the liquid alloy feed port.

[0043] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.007% of the total mass of zirconium and hafnium, meeting the requirements for hafnium content in nuclear-grade zirconium.

[0044] Example 6

[0045] Electrolysis reaction in such Figure 1The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 1:1, and 10g of zirconium powder (containing 2.2% hafnium by mass) was added as the solute metal. A graphite rod was used as the anode electrode, stainless steel as the cathode electrode, and refractory ceramic as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of cathode electrolyte was prepared in the cathode chamber using NaCl, KCl, and ZrCl2 at a mass ratio of 1:1:0.02. Under an argon atmosphere, the mixture was heated to 900℃ at a rate of 10℃ / min and held for 1 hour. Simultaneously, ZrO2 (containing 1.8% hafnium by mass) was slowly added to the anode chamber while a voltage was applied, controlling the current density to be 0.02 A·cm⁻¹. -2 Zirconium ions in the anode electrolyte are continuously reduced and enter the liquid alloy, while hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After electrolysis for 6 hours, a sample is taken from the liquid alloy feed port.

[0046] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.009% of the total mass of zirconium and hafnium, meeting the requirements for hafnium content in nuclear-grade zirconium.

[0047] Example 7

[0048] Electrolysis reaction in such Figure 1 The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 1:1, and 10g of zirconium powder (containing 5.2% hafnium by mass) was added as the solute metal. A graphite rod was used as the anode electrode, stainless steel as the cathode electrode, and refractory ceramic as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of NaCl, KCl, and ZrCl2 were added to the cathode chamber as the cathode electrolyte in a mass ratio of 1:1:0.02. Under an argon atmosphere, the mixture was heated to 900℃ at a rate of 10℃ / min and held for 1 hour. Potassium fluorozirconate (containing 2.2% hafnium by mass) was added to the anode chamber while a voltage was applied, controlling the current density to be 0.02 A·cm⁻¹. -2 Zirconium ions in the anode electrolyte are continuously reduced and enter the liquid alloy, while hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After electrolysis for 6 hours, a sample is taken from the liquid alloy feed port.

[0049] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.012% of the total mass of zirconium and hafnium.

[0050] Example 8

[0051] Electrolysis reaction in such Figure 1The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 9:1, and 90g of zirconium powder (containing 2.2% hafnium by mass) was added as the solute metal. Zirconium was used as the anode electrode (containing 6.2% hafnium by mass), stainless steel as the cathode electrode, and refractory ceramic as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of cathode electrolyte was prepared in the cathode chamber using NaCl, KCl, and ZrCl2 at a mass ratio of 1:1:0.02. Under an argon atmosphere, the mixture was heated to 950℃ at a rate of 10℃ / min and held for 1 hour. A voltage was then applied, and the current density was controlled at 0.02 A·cm⁻¹. -2 Zirconium ions in the anode electrolyte are continuously reduced and enter the liquid alloy, while hafnium in the liquid alloy is oxidized and enters the cathode electrolyte. After electrolysis for 6 hours, a sample is taken from the liquid alloy feed port.

[0052] Elemental analysis of the metallic phase in the liquid alloy revealed that the hafnium content accounted for 0.013% of the total mass of zirconium and hafnium.

[0053] The parameters for variations in Examples 9 and 10 are shown in Table 1. Other parameters are the same as in Example 1. The experimental results are shown in Table 1.

[0054] Table 1

[0055]

[0056] Comparative Example 1

[0057] Electrolysis reaction in such Figure 1 The electrolytic process was carried out in the cell shown. 500g of molten metal was prepared at a copper-tin ratio of 9:1. Graphite rods were used as anode electrodes, stainless steel as cathode electrodes, and refractory ceramics as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of cathode electrolyte was prepared by adding NaCl, KCl, and ZrCl4 at a mass ratio of 1:1:0.02 in the cathode chamber. Under an argon atmosphere, the mixture was heated to 800℃ at a rate of 10℃ / min and held for 1 hour. Potassium fluorozirconate (with hafnium content accounting for 2.2% of the total mass of zirconium and hafnium) was added to the anode chamber while voltage was applied. After 6 hours, a sample was taken from the liquid alloy inlet.

[0058] Elemental analysis of the metallic phase in the liquid alloy revealed a low zirconium content, making zirconium-hafnium separation impossible.

[0059] Comparative Example 2

[0060] Electrolysis reaction in such Figure 1The electrolytic cell was used in the following process: 500g of molten metal was prepared at a copper-tin ratio of 9:1, and 90g of zirconium powder (of which hafnium accounted for 2.2% of the total mass of zirconium and hafnium) was added as the solute metal. Graphite rods were used as anode electrodes, stainless steel as cathode electrodes, and refractory ceramics were used as the cell lining. 300g of NaCl-KCl electrolyte was prepared as the anode electrolyte in the anode chamber at a mass ratio of 1:1. 300g of cathode electrolyte was prepared in the cathode chamber by adding NaCl, KCl, and ZrCl4 at a mass ratio of 1:1:0.02. Under argon atmosphere protection, the temperature was heated to 800℃ at a rate of 10℃ / min and held for 1 hour before applying voltage. Electrolysis continued for 6 hours, and samples were taken from the liquid alloy inlet.

[0061] Elemental analysis of the metallic phase in the liquid alloy showed that the zirconium-hafnium ratio in the alloy remained unchanged.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An electrochemical process for zirconium-hafnium separation, characterized in that, The method comprises: An electrolytic cell with an anode chamber and a cathode chamber, an anode electrolyte and a cathode electrolyte are arranged in the anode chamber and the cathode chamber respectively, an anode electrode is inserted into the anode electrolyte, and a cathode electrode is inserted into the cathode electrolyte; the anode chamber and the cathode chamber are separated by a liquid alloy, and the anode electrode and the cathode electrode are not in contact with the liquid alloy; The liquid alloy comprises a solute metal and a melt metal, the solute metal is coarse zirconium, and the coarse zirconium contains hafnium elements; the melt metal has a lower metal activity than zirconium; The electric current electrolysis is carried out under the protection of argon, and the electrolysis reaction temperature is 400-1100 DEG C, and the anode current density is 0.002-0.5 A·cm -2 ; The material of the anode electrode is selected from one of graphite, copper and zirconium; When the material of the anode electrode is graphite, a zirconium-containing material is added into the anode chamber, and the zirconium-containing material is a halide or an oxide of zirconium; When the material of the anode electrode is copper, the anode electrolyte is selected from one or more of CuCl2 and LiF, NaF, KF, LiCl, NaCl, KCl and CaCl2; when the material of the anode electrode is graphite or zirconium, the anode electrolyte is selected from one or more of ZrCl4, ZrCl2, ZrCl3, Na2ZrF6 and K2ZrF6 and one or more of LiF, NaF, KF, LiCl, NaCl, KCl and CaCl2.

2. The method of claim 1, wherein, The zirconium-containing material is selected from one or more of Na2ZrCl6, K2ZrCl6, Na2ZrF6, K2ZrF6, ZrO2, ZrCl2, ZrCl3 and ZrCl4.

3. The method of claim 1, wherein, When the material of the anode electrode is copper or coarse zirconium, the anode chamber does not need to add a zirconium-containing material.

4. The method of claim 1, wherein, The melt metal is selected from one or more of copper, lead, zinc, tin and bismuth, and the formed liquid alloy has a melting point lower than 1100℃.

5. The method of claim 1, wherein, The cathode electrolyte is selected from one or more of LiF, NaF, KF, LiCl, NaCl, KCl and CuCl2, and a halide of zirconium and / or hafnium is dissolved in the cathode electrolyte, and the halide of zirconium and / or hafnium is selected from one or more of ZrCl4, ZrCl2, ZrCl3, HfCl4, HfCl2, HfCl3, Na2ZrCl6, K2ZrCl6, Na2HfCl6, K2HfCl6, Na2ZrF6, K2ZrF6, Na2HfF6 and K2HfF6.

6. The method of claim 5, wherein, The halide of zirconium and / or hafnium is dissolved in the cathode electrolyte.

7. The method of claim 1, wherein, The material of the cathode electrode is stainless steel, zirconium, titanium or tungsten.

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