Method for preparing metal zirconium from zirconium-hafnium alloy through valence state regulation and control

Abstract

The embodiment of the invention discloses a method for preparing metal zirconium from zirconium-hafnium alloy through valence state regulation and control. Comprising the following steps: adding tetravalent hafnium salt into a zirconium-hafnium alloy raw material as a valence regulator to obtain a reaction raw material; adding chloride eutectic salt into the reaction raw materials as a reaction medium; under set conditions, metal hafnium in the zirconium-hafnium alloy reacts with tetravalent hafnium salt to generate divalent hafnium ions; putting a reaction product system into a high-temperature-resistant metal crucible, and carrying out electrolysis under set conditions by taking a zirconium rod as an anode, a high-purity zirconium rod as a cathode and chloride eutectic salt in the reaction product system as electrolyte; in the electrolysis process, the metal zirconium of the anode is oxidized into zirconium ions to enter the electrolyte, the zirconium ions in the electrolyte migrate to the cathode to be separated out and precipitated into nuclear-grade metal zirconium with the purity being 99.95% or above, and metal hafnium is left in the electrolyte in the form of ions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical metallurgy, and particularly relates to a method for preparing metallic zirconium from zirconium-hafnium alloy by valence state regulation. BACKGROUND

[0002] Zirconium and hafnium are important nuclear industry and high-performance alloy materials, and the purity and performance thereof have a decisive influence on downstream applications. Since zirconium and hafnium have similar chemical properties and atomic radii, they often coexist in ores in nature, and the separation process is extremely complex, becoming a big problem in material preparation. Existing zirconium-hafnium separation technologies mainly rely on multi-step chemical extraction, ion exchange and solvent extraction processes. These methods not only have a complex process flow and many steps, but also have harsh operating conditions, often requiring high temperature and high pressure environments, resulting in high overall energy consumption. In addition, the traditional zirconium-hafnium separation process has a long cycle and takes a long time, which seriously restricts the large-scale preparation and application promotion of nuclear-grade high-purity metallic zirconium. Especially in the production of nuclear-grade zirconium, the strict control of hafnium content is directly related to the safety and service life of the nuclear reactor, so that efficient, environmentally friendly and economical zirconium-hafnium separation and purification technologies need to be broken through.

[0003] Most of the separation processes on the market not only have high energy consumption, but also use a large amount of chemical reagents, generating a large burden on the environment in the form of waste liquid and waste residue, increasing the subsequent treatment cost and ecological risk. SUMMARY

[0004] Therefore, the embodiments of the present application disclose a method for preparing metallic zirconium from zirconium-hafnium alloy by valence state regulation, comprising:

[0005] A tetravalent hafnium salt is added to the zirconium-hafnium alloy raw material as a valence state regulator to obtain a reaction raw material;

[0006] A chloride eutectic salt is added to the reaction system as a reaction medium;

[0007] Under the set conditions, the reaction raw material reacts in the medium, and the metallic hafnium in the zirconium-hafnium alloy reacts with the tetravalent hafnium salt to generate divalent hafnium ions;

[0008] The reaction product system is placed in a high-temperature-resistant metal crucible, a high-purity zirconium rod is used as a cathode, a zirconium rod is used as an anode, and the chloride eutectic salt in the reaction product system is used as an electrolyte, and electrolysis is carried out under the set conditions. During the electrolysis process, the metallic zirconium of the anode is oxidized into zirconium ions into the electrolyte, and the zirconium ions in the electrolyte migrate to the cathode to be precipitated as metallic zirconium. The obtained metallic zirconium has a purity of more than 99.95%.

[0009] Further, some embodiments disclose a method for preparing metallic zirconium from zirconium-hafnium alloy by valence state regulation, and the addition amount of the valence state regulator is 1.1-11:1 in mole ratio to the hafnium in the zirconium-hafnium alloy.

[0010] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the temperature for the reaction of the raw materials is set to 750-1000℃, and the time is 0.5-10h.

[0011] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the electrolysis voltage is 0.5-3.2V, the electrolysis temperature is set to 450-1000℃, and the electrolysis time is 0.5-200h.

[0012] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the chloride eutectic salt comprises sodium chloride-potassium chloride eutectic salt, lithium chloride-potassium chloride eutectic salt, lithium chloride-sodium chloride-potassium chloride eutectic salt.

[0013] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the salt containing tetravalent hafnium comprises hafnium chloride, hafnium fluoride, hafnium sulfate.

[0014] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the high-temperature resistant metal crucible comprises nickel crucible, molybdenum crucible, zirconium crucible.

[0015] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the chloride eutectic salt is supplemented according to the set amount during the electrolysis process.

[0016] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the electrolysis process is constant potential electrolysis.

[0017] Some embodiments disclose a method for preparing metal zirconium from zirconium-hafnium alloy by valence state regulation, wherein the valence state of hafnium in the zirconium-hafnium alloy is adjusted, thereby effectively separating metal zirconium ions from metal hafnium ions during the electrolysis process, improving the purity and efficiency of the cathodic deposition of metal zirconium, and preparing high-purity nuclear-grade metal zirconium, which has good application prospects. DETAILED DESCRIPTION

[0018] Herein, the term "embodiment" is not necessarily construed as superior or better than other embodiments. In the performance index test of the embodiments, unless otherwise specified, the conventional test method in the art is used. It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not intended to limit the disclosure of the present application.

[0019] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs; as the test methods and technical means not specifically noted in the present application refer to the experimental methods and technical means generally used by those skilled in the art.

[0020] The terms “basic” and “approximately” used in this document are to describe small fluctuations. For example, they can mean less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in range format in this document are used for convenience and brevity only, and should therefore be flexibly interpreted to include not only the explicitly listed values ​​that define the range, but also all independent values ​​or subranges contained within that range. For example, a numerical range of “1–5%” should be interpreted to include not only the explicitly listed values ​​from 1% to 5%, but also the independent values ​​and subranges within the indicated range. Thus, this numerical range includes independent values ​​such as 2%, 3.5%, and 4%, and subranges such as 1%–3%, 2%–4%, and 3%–5%, etc. This principle also applies to ranges that list only one value. Furthermore, this interpretation applies regardless of the width of the range or the characteristics described.

[0021] In this document, including in the claims, conjunctions such as "comprising," "including," "with," "having," "containing," "involving," and "accommodating" are understood to be open-ended, meaning "including but not limited to." Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0022] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0023] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0024] In some embodiments, the method for preparing metallic zirconium from zirconium-hafnium alloys by valence state control includes:

[0025] A tetravalent hafnium salt is added to the zirconium-hafnium alloy raw material as a valence modifier to obtain the reaction raw material; typically, the molar ratio of the amount of valence modifier added to hafnium in the zirconium-hafnium alloy is 1.1 to 11:1; the tetravalent hafnium salt includes hafnium tetrachloride, hafnium fluoride, hafnium sulfate and other salts containing tetravalent hafnium ions;

[0026] Chloride eutectic salts are added to the reaction raw materials as a reaction medium; typically, chloride eutectic salts include sodium chloride-potassium chloride eutectic salts, lithium chloride-potassium chloride eutectic salts, and lithium chloride-sodium chloride-potassium chloride eutectic salts.

[0027] Under set conditions, the reactants react in the reaction medium at a temperature of 750–1000℃ for 0.5–10 h. In the zirconium-hafnium alloy, metallic hafnium reacts with tetravalent hafnium salt to generate divalent hafnium ions. Typically, the conversion of metallic hafnium in the zirconium-hafnium alloy into divalent hafnium ions widens the deposition potential difference between divalent hafnium and zirconium ions. This allows for control of the appropriate electrolysis potential in subsequent electrolysis processes. At the anode, metallic zirconium is oxidized to zirconium ions, which are further deposited as metal at the cathode. Meanwhile, divalent hafnium ions remain in the electrolyte, achieving effective separation of zirconium and hafnium and yielding high-purity metallic zirconium.

[0028] The reaction product system is placed in a high-temperature resistant metal crucible, with a high-purity zirconium rod as the cathode and the zirconium rod as the anode. The chloride eutectic salt in the reaction product system serves as the electrolyte, and electrolysis is carried out under set conditions. During electrolysis, the metallic zirconium at the anode is oxidized into zirconium ions, which enter the electrolyte. The zirconium ions in the electrolyte migrate to the cathode and precipitate as metallic zirconium. The purity of the obtained metallic zirconium is above 99.95%. Typically, the high-temperature resistant metal crucible includes nickel crucibles and molybdenum crucibles; the high-purity metal electrode includes a high-purity zirconium electrode; the electrolysis process is constant potential electrolysis, with an electrolysis voltage of 0.5–3.2 V, an electrolysis temperature set at 450–1000 °C, and an electrolysis time of 0.5–200 h.

[0029] The technical details are further illustrated below with reference to the embodiments.

[0030] Example 1

[0031] Example 1 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0032] Using 3g of zirconium metal alloy containing 2.3wt% hafnium as raw material, hafnium tetrachloride was added as a valence state regulating additive at 1.1 times the molar amount of hafnium metal to obtain the reaction raw material;

[0033] 30g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set to 750℃. After 1 hour of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0034] A nickel-based metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 120g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium electrode was used as the cathode, and electrolysis was performed at a constant potential at 750℃. The electrolysis voltage was set to 1.0V, and the electrolysis time was 5 hours. Zirconium metal was obtained from the cathode.

[0035] The final nuclear-grade zirconium metal obtained has a purity of 99.95%.

[0036] Example 2

[0037] Example 2 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0038] Using 5g of zirconium metal alloy containing 2.5wt% hafnium as raw material, hafnium fluoride was added as a valence state regulating additive at 5 times the molar amount of hafnium metal to obtain the reaction raw material;

[0039] 50g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set to 1000℃. After 5 hours of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0040] A zirconium metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 100g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium metal electrode was used as the cathode, and constant potential electrolysis was performed at 450℃. The electrolysis voltage was set to 2.0V, and the electrolysis time was 10 hours. Zirconium metal was obtained from the cathode.

[0041] The final nuclear-grade zirconium metal obtained had a purity of 99.96%.

[0042] Example 3

[0043] Example 3 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0044] Using 10g of zirconium metal alloy containing 20wt% hafnium as raw material, hafnium tetrachloride was added as a valence state regulating additive at 11 times the molar amount of hafnium metal to obtain the reaction raw material;

[0045] 80g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set to 800℃. After reacting for 10 hours, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0046] A nickel-based metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 210g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium metal electrode was used as the cathode, and constant potential electrolysis was performed at 1000℃. The electrolysis voltage was set to 3.0V, and the electrolysis time was 50 hours. Zirconium metal was obtained from the cathode.

[0047] The final obtained nuclear-grade zirconium metal has a purity of 99.98%.

[0048] Example 4

[0049] Example 4 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0050] Using 8g of a zirconium alloy containing 5.8wt% hafnium as raw material, hafnium sulfate was added as a valence state regulating additive at a ratio of 3 times the molar amount of hafnium to obtain the reaction raw material;

[0051] 60g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set to 900℃. After 8 hours of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0052] A molybdenum metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 150g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium metal electrode was used as the cathode, and constant potential electrolysis was performed at 850℃. The electrolysis voltage was set to 0.5V, and the electrolysis time was 2 hours. Zirconium metal was obtained from the cathode.

[0053] The final obtained nuclear-grade zirconium metal has a purity of 99.98%.

[0054] Example 5

[0055] Example 5 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0056] Using 50g of zirconium metal alloy containing 2.0wt% hafnium as raw material, hafnium sulfate was added as a valence state regulating additive at 8 times the molar amount of hafnium metal to obtain the reaction raw material;

[0057] 300g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set at 750℃. After 8 hours of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0058] A nickel-based metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 420g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium metal electrode was used as the cathode, and constant potential electrolysis was performed at 820℃. The electrolysis voltage was set to 3.2V, and the electrolysis time was 100 hours. Zirconium metal was obtained from the cathode.

[0059] The final nuclear-grade zirconium metal obtained had a purity of 99.97%.

[0060] Example 6

[0061] Example 6 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0062] Using 1g of zirconium metal alloy containing 1.5wt% hafnium as raw material, hafnium fluoride was added as a valence state regulating additive at twice the molar amount of hafnium metal to obtain the reaction raw material;

[0063] 30g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set to 800℃. After 3 hours of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0064] A nickel-based metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 120g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium electrode was used as the cathode, and electrolysis was performed at a constant potential at 750℃. The electrolysis voltage was set to 1.5V, and the electrolysis time was 0.5 hours. Zirconium metal was obtained from the cathode.

[0065] The final nuclear-grade zirconium metal obtained has a purity of 99.95%.

[0066] Example 7

[0067] Example 7 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0068] Using 7g of a zirconium alloy containing 1.2wt% hafnium as raw material, hafnium sulfate was added as a valence state regulating additive at 1.1 times the molar amount of hafnium to obtain the reaction raw material;

[0069] 20g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set at 920℃. After 8 hours of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0070] A nickel-based metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 180g of sodium chloride-potassium chloride eutectic salt. A high-purity zirconium electrode was used as the cathode, and electrolysis was performed at a constant potential at 800℃. The electrolysis voltage was set to 2.5V, and the electrolysis time was 20 hours. Zirconium metal was obtained from the cathode.

[0071] The final nuclear-grade zirconium metal obtained had a purity of 99.97%.

[0072] Example 8

[0073] Example 8 discloses a method for preparing metallic zirconium from zirconium-hafnium alloys by controlling valence state, comprising:

[0074] Using 120g of zirconium metal alloy containing 0.3wt% hafnium as raw material, hafnium tetrachloride was added as a valence state regulating additive at 4 times the molar amount of hafnium metal to obtain the reaction raw material;

[0075] 500g of sodium chloride-potassium chloride eutectic salt was added to the reaction raw materials as a reaction medium. The valence state control temperature was set at 950℃. After 10 hours of reaction, metallic hafnium was converted into divalent hafnium ions, and a reaction product system containing divalent hafnium ions was obtained.

[0076] A nickel-based metal crucible was used, with a zirconium rod as the electrolytic anode. A reaction product system containing divalent hafnium ions was added to the crucible, followed by the addition of 120g of sodium chloride-potassium chloride eutectic salt. A high-purity molybdenum electrode was used as the cathode, and electrolysis was performed at a constant potential at 1000℃. The electrolysis voltage was set to 2.8V, and the electrolysis time was 12 hours. Zirconium metal was obtained from the cathode.

[0077] The final nuclear-grade zirconium metal obtained has a purity of 99.95%.

[0078] This invention discloses a method for preparing nuclear-grade zirconium metal from zirconium-hafnium alloys via valence-state controlled molten salt electrolysis. The method uses zirconium alloys containing different proportions of hafnium as raw materials. Tetravalent hafnium salts are added to the raw materials at a ratio of 1.1 to 11 times the molar amount of hafnium as valence-state controlling additives, and chloride eutectic salts are added as the reaction medium. The valence-state controlling temperature is controlled at 750–1000°C, and the controlling time is within the range of 0.5–10 hours. During the constant-potential electrolysis process, a high-temperature resistant metal crucible is used as the electrolysis anode, and a high-purity metal electrode is used as the cathode. Molten salt electrolysis is performed at a high temperature of 750°C–1000°C, with the electrolysis voltage set at 0.5V–3.2V and the electrolysis time ranging from 0.5 hours to 200 hours. The final prepared nuclear-grade zirconium metal has a purity of 99.95% or higher.

[0079] This invention achieves effective control over the valence state of hafnium by precisely adjusting the addition ratio of hafnium tetrachloride and the valence state control time, thereby improving the purity and selective separation efficiency of zirconium. Using a chloride eutectic salt system as the high-temperature electrolysis medium, combined with a metal crucible as the anode material, ensures the stability and durability of the electrolysis process. This method is simple, easy to operate, and has low energy consumption. It produces high-quality nuclear-grade zirconium metal that meets the stringent requirements of the nuclear industry for high-purity zirconium materials, demonstrating good economic benefits and significant potential for widespread application.

[0080] The technical solutions and technical details disclosed in the embodiments of this application are merely illustrative of the inventive concept of this application and do not constitute a limitation on the technical solutions of this application. Any conventional changes, substitutions or combinations made to the technical details disclosed in this application have the same inventive concept as this application and are within the protection scope of the claims of this application.

Claims

1. A method for preparing metallic zirconium from zirconium-hafnium alloys by valence state control, characterized in that, include: A tetravalent hafnium salt is added to the zirconium-hafnium alloy raw material as a valence state modifier to obtain the reaction raw material; Chloride eutectic salt is added to the reaction raw materials as a reaction medium; Under the set conditions, the reactants react in the medium, and metallic hafnium in the zirconium-hafnium alloy reacts with tetravalent hafnium salt to generate divalent hafnium ions; The reaction product system is placed in a high-temperature resistant metal crucible, with a high-purity zirconium rod as the cathode and a zirconium rod as the anode. The chloride eutectic salt in the reaction product system is used as the electrolyte, and electrolysis is carried out under set conditions. During the electrolysis process, the metallic zirconium at the anode is oxidized into zirconium ions and enters the electrolyte. The zirconium ions in the electrolyte migrate to the cathode and precipitate as metallic zirconium. The obtained metallic zirconium has a purity of over 99.95%, while metallic hafnium remains in the electrolyte in the form of ions.

2. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The molar ratio of the valence modifier to hafnium in the zirconium-hafnium alloy is 1.1 to 11:

1.

3. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The reaction temperature of the reactants is set at 750–1000℃, and the reaction time is 0.5–10 h.

4. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The electrolysis voltage is 0.5–3.2V, the electrolysis temperature is set to 450–1000℃, and the electrolysis time is 0.5–200h.

5. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The chloride eutectic salts include sodium chloride-potassium chloride eutectic salts, lithium chloride-potassium chloride eutectic salts, and lithium chloride-sodium chloride-potassium chloride eutectic salts.

6. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The tetravalent hafnium salts include hafnium tetrachloride, hafnium fluoride, and hafnium sulfate.

7. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The high-temperature resistant metal crucibles include nickel crucibles, molybdenum crucibles, and zirconium crucibles.

8. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, During the electrolysis process, chloride eutectic salt is added in a set amount.

9. The method for preparing metallic zirconium from zirconium-hafnium alloy by valence state control according to claim 1, characterized in that, The electrolysis process is constant potential electrolysis.