Method for preparing zirconium metal with controllable morphology based on regulation and control of active cathode

Abstract

The embodiment of the invention discloses a method for preparing morphology-controllable metal zirconium based on active cathode regulation and control. The method comprises the following steps: forming an electrolysis system by taking crude metal zirconium as an anode, active solid metal as a cathode and eutectic salt electrolyte containing K2ZrF6 as molten salt electrolyte; and the electrolysis system carries out electrolysis under different electrolysis conditions, and high-purity zirconium with different morphologies is obtained on the surface of the cathode. According to the method, on the basis of a high-temperature fused salt electrolysis method, active solid metal serves as a cathode, accurate regulation and control over the zirconium crystal morphology are achieved by regulating and controlling the power supply mode and the current density of electrolysis and utilizing dynamic dissolution-deposition of an active solid metal cathode material, and meanwhile the active solid metal serves as an electrode; the Zr / Hf separation coefficient can be increased, the product purity is improved, and the material cost and the energy consumption are reduced; according to the method, separation and morphology control are achieved through a one-step method, the technological process is simple, operation is convenient, harmful gas is not generated, and the method has good application prospects in the fields of nuclear industry, additive manufacturing and the like.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical metallurgy technology, specifically relating to a method for preparing morphology-controllable metallic zirconium based on active cathode regulation. Background Technology

[0002] Currently, the main method for large-scale industrial production of metallic zirconium is still the Kroll process, which involves the magnesothermic reduction of zirconium tetrachloride (ZrCl4) to produce sponge zirconium. However, this method suffers from problems such as high energy consumption (reaction temperature needs to reach 800-900℃), severe chlorine pollution, and a long process flow (requiring subsequent vacuum arc melting for densification).

[0003] In contrast, molten salt electrolysis offers a series of significant advantages in the preparation of metallic zirconium, including high selectivity, high efficiency, low energy consumption, ease of operation, and wide applicability. Patent document CN108866578A discloses a process for preparing nuclear-grade high-purity zirconium by molten salt electrolysis of zirconium and hafnium separation, employing an inert cathode (such as molybdenum, tantalum, or titanium) in a LiCl-KCl-ZrCl4 molten salt system. However, this method has significant problems: firstly, the poor wettability between the inert cathode surface and zirconium leads to the formation of dendritic structures during zirconium deposition, affecting the mechanical properties and subsequent processing performance of the product; secondly, traditional electrolysis processes lack effective means to control the morphology of zirconium deposition, making it difficult to prepare zirconium materials with specific structures according to application requirements. Summary of the Invention

[0004] In view of this, embodiments of the present invention disclose a method for preparing morphology-controllable metallic zirconium based on active cathode modulation, comprising:

[0005] An electrolysis system is constructed using crude zirconium metal as the anode, an active solid metal as the cathode, and a eutectic salt electrolyte containing K2ZrF6 as the molten salt electrolyte.

[0006] Electrolysis was carried out under different electrolysis conditions, and high-purity zirconium with different morphologies was obtained on the cathode surface.

[0007] Furthermore, some embodiments disclose methods for preparing morphology-controllable metallic zirconium based on active cathode regulation, wherein the electrolysis power supply includes a constant current power supply and a pulse power supply.

[0008] Some embodiments disclose methods for preparing morphology-controllable metallic zirconium based on active cathode modulation, wherein the current density of the constant current power supply is 0.01–10 A·cm. -2 The current density of the pulse power supply is 0.2–10 A·cm. -2 .

[0009] Some embodiments disclose a method for preparing morphology-controllable metallic zirconium based on active cathode modulation, wherein the pulse period of the pulse power supply is 2 to 20 minutes, and the duty cycle is 0.1 to 0.9.

[0010] Some embodiments disclose a method for preparing morphology-controllable metallic zirconium based on active cathode regulation, wherein the electrolysis temperature is set to 450–850 °C.

[0011] Some embodiments disclose a method for preparing morphology-controllable metallic zirconium based on active cathode regulation, wherein the eutectic salt electrolyte is a combination of at least two of LiCl, NaCl, and KCl, and the mass content of K2ZrF6 in the molten salt electrolyte is 1-20 wt.%.

[0012] Some embodiments disclose a method for preparing morphology-controllable metallic zirconium based on active cathode modulation, wherein the active solid metal includes copper and nickel.

[0013] Some embodiments disclose a method for preparing morphology-controllable metallic zirconium based on active cathode control, wherein the crude metallic zirconium is metallic zirconium containing metallic hafnium.

[0014] This invention discloses a method for preparing morphology-controllable metallic zirconium based on an active cathode. Utilizing a high-temperature molten salt electrolysis method, an active solid metal is used as the cathode. By controlling the electrolysis's power supply method and current density, and leveraging the dynamic dissolution-deposition of the active solid metal cathode material, precise control of the zirconium crystal morphology is achieved, avoiding the shortcomings of inert cathodes (such as molybdenum and tungsten) which cannot actively control zirconium crystallization behavior. Simultaneously, using an active solid metal as the electrode can improve the Zr / Hf separation coefficient, increase product purity, and reduce material costs and energy consumption. This method achieves separation and morphology control in a one-step process, with a simple flow, easy operation, and no harmful gas generation, showing promising application prospects in the nuclear industry, additive manufacturing, and other fields. Attached Figure Description

[0015] Figure 1 Some embodiments disclose zirconium metal morphology images; Figure 1 In the figures, (a) is a scanning electron microscope (SEM) image of the dense zirconium coating obtained in Example 1 of the present invention; (b) is a scanning electron microscope (SEM) image of the porous metallic zirconium obtained in Example 2 of the present invention; (c) is a scanning electron microscope (SEM) image of the metallic zirconium particles obtained in Example 4 of the present invention; and (d) is a scanning electron microscope (SEM) image of the dendritic metallic zirconium obtained in Example 5 of the present invention. Detailed Implementation

[0016] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in these embodiments of the invention, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in these embodiments is merely for describing particular implementations and is not intended to limit the scope of the disclosure of these embodiments.

[0017] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain; other experimental methods and technical means not specifically noted in the embodiments of this invention refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0018] 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.

[0019] 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.

[0020] To better illustrate the content of this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the invention can be practiced 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 the invention.

[0021] Without conflict, the technical features disclosed in the embodiments of the present invention can be combined arbitrarily, and the resulting technical solutions belong to the content disclosed in the embodiments of the present invention.

[0022] In some embodiments, this invention discloses a method for preparing morphology-controllable metallic zirconium based on active cathode modulation, comprising:

[0023] An electrolytic system is formed by using crude zirconium metal as the anode, an active solid metal as the cathode, and a eutectic salt electrolyte containing K2ZrF6 as the molten salt electrolyte; generally, the crude zirconium metal is zirconium metal containing hafnium metal.

[0024] Generally, active solid metals include copper and nickel. This invention introduces an active solid metal cathode, such as copper or nickel, and changes the deposition thermodynamic / kinetic path of zirconium through electrochemical alloying. Combined with adsorption regulation and selective dissolution at the active electrode interface, it achieves the preparation of zirconium with controllable morphology from dense coating to porous structure. By adjusting the electrolysis parameters, the crystallization behavior of zirconium can be further controlled, achieving dual optimization of morphology and composition.

[0025] Electrolysis was carried out under different electrolysis conditions, resulting in high-purity zirconium with different morphologies on the cathode surface. Typically, the electrolysis power source is a constant current source with a current density of 0.01–10 A·cm⁻¹. -2 The electrolysis power supply can be a pulsed power supply, with a current density of 0.2–10 A·cm. -2 The pulse period of the pulse power supply is 2–20 min, with a duty cycle of 0.1–0.9. Typically, the morphology of the electrolytic product, metallic zirconium, includes dense layered structures, nanoparticles, and porous structures.

[0026] In some embodiments, crude zirconium is used as the anode, an active solid metal as the cathode, and a eutectic sodium-potassium salt or lithium-potassium salt containing a certain proportion of K2ZrF6 as the electrolyte. Both the crude zirconium anode and the active cathode are inserted into the electrolyte molten salt at a certain depth. During electrolysis, the morphology of zirconium crystals is precisely controlled by adjusting the power supply method and current density and utilizing the dynamic dissolution-deposition of the active cathode material. During electrolysis, the deposited metallic zirconium adheres to the surface of the active cathode. After electrolysis, the active cathode is ultrasonically cleaned and the product is collected. After washing and drying with deionized water, for example, drying under vacuum conditions, high-purity metallic zirconium with controllable morphology can be obtained.

[0027] Typically, during electrolysis, crude zirconium at the anode loses electrons and is oxidized into high-valence zirconium ions, which enter the molten electrolyte. The high-valence zirconium ions in the molten salt gain electrons at the cathode and are reduced, depositing on the surface of the active solid metal serving as the cathode. Since the active solid metal can effectively improve the zirconium / hafnium separation coefficient and promote highly selective separation of zirconium and hafnium, the purity of the electrolytic product zirconium can be effectively improved. By altering the deposition thermodynamics / kinetics of zirconium through electrochemical alloying, combined with interfacial adsorption control and selective dissolution, controllable morphology zirconium formation, from dense coatings to porous structures, can be achieved. Taking the active solid electrode nickel as an example, firstly, in the initial deposition stage, Zr in the molten salt... 4+ Ions are directly reduced on the nickel electrode surface, forming a dense zirconium coating. When the nickel electrode undergoes an in-situ alloying reaction with the deposited zirconium, thermodynamically stable Ni-Zr intermetallic compounds, such as NiZr2, are formed. This alloying process shifts the apparent deposition potential of zirconium positively, thereby lowering the reduction barrier and altering the thermodynamic driving force of deposition. At the kinetic level, electrochemical alloying further modulates the deposition behavior of zirconium. Under high overpotentials, Zr... 4+ Rapid reduction tends to form dense layers, but the formation of the Ni-Zr alloy phase acts as an "atomic trap," slowing down Zr surface diffusion and promoting three-dimensional island-like nucleation rather than layered growth. This non-uniform deposition leads to differences in local deposition rates, ultimately resulting in a porous structure of deposited zirconium.

[0028] Electrolysis generally uses constant current electrolysis and pulse electrolysis methods; taking constant current electrolysis as an example, the current is 0.5–1.2 A / cm. 2 At low current densities, Zr 4+ Slow reduction occurs on the cathode surface, where atoms diffuse to form uniform crystal nuclei, which then grow epitaxially along the close-packed planes to form a columnar crystal structure; 1.5–2.5 A / cm 2 At moderate current densities, Zr and Cu form an amorphous alloy Cu-Zr. Subsequent acid leaching with HNO3 or similar methods dissolves the Cu phase, leaving a three-dimensional nanoporous Zr framework; greater than 2.5 A / cm². 2 High current density can lead to concentration polarization, Zr 4+ At the cathode tip, preferential reduction occurs, forming fractal dendrites; ultra-high current density leads to instantaneous nucleation of Zr in the molten salt. 4+ It is rapidly depleted, forming nanoscale particles that detach from the cathode.

[0029] Generally, the eutectic salt electrolyte is a combination of at least two of LiCl, NaCl, and KCl, and the mass content of K2ZrF6 in the molten salt electrolyte is 1–20 wt.%. The eutectic salt electrolyte can be NaCl-KCl eutectic salt, LiCl-KCl eutectic salt, LiCl-NaCl eutectic salt, or LiCl-NaCl-KCl eutectic salt.

[0030] Generally, the electrolysis temperature is set between 450 and 850℃. Due to differences in the eutectic point of molten salts in different systems, the electrolysis temperature of the constant current electrolysis process can be controlled by adjusting the temperature of the molten salt, thereby controlling the ion migration rate in the electrolyte and achieving control and regulation of the electrolysis rate.

[0031] The technical details are further illustrated below with reference to the embodiments.

[0032] Example 1

[0033] An electrolytic system was formed using hafnium-containing crude zirconium as the anode, a copper plate as the cathode, and a NaCl-KCl eutectic salt containing 10 wt% K2ZrF6 as the electrolyte; the hafnium content in the crude zirconium was 0.18 wt.%.

[0034] The electrolysis temperature was set to 750℃, and the electrolysis current density was set to 0.1 A·cm. -2 Perform constant current electrolysis;

[0035] After electrolysis, the electrolysis products were collected, washed, and dried to obtain a dense zirconium coating with a hafnium content of 0.05 wt.%. SEM images are shown below. Figure 1 As shown in (a).

[0036] Example 2

[0037] An electrolytic system was formed using hafnium-containing crude zirconium as the anode, high-purity copper foam as the cathode, and NaCl-KCl eutectic salt containing 10wt% K2ZrF6 as the electrolyte; the hafnium content in the crude zirconium was 0.18wt.%.

[0038] The electrolysis temperature was set to 750℃, the pulse frequency of the pulse power supply was set to 200Hz, the duty cycle to 40%, and the current density to 2.0A·cm. -2 Perform pulse electrolysis;

[0039] After electrolysis, the electrolysis products were collected, washed, and dried to obtain porous metallic zirconium with a hafnium content of 0.047 wt.%, as shown in the SEM image. Figure 1 As shown in (b).

[0040] Example 3

[0041] An electrolytic system was formed using hafnium-containing crude zirconium as the anode, a nickel plate as the cathode, and a NaCl-KCl eutectic salt containing 10 wt% K2ZrF6 as the electrolyte; the hafnium content in the crude zirconium was 0.18 wt.%.

[0042] The electrolysis temperature was set to 750℃, the pulse frequency of the pulse power supply was set to 50Hz, the duty cycle to 60%, and the peak current density to 0.2A·cm. -2 Pulse electrolysis is performed with a reverse pulse ratio of 7%.

[0043] After electrolysis, the electrolysis products were collected, washed, and dried to obtain uniform and porous metallic zirconium with a hafnium content of 0.07 wt.%.

[0044] Example 4

[0045] An electrolytic system was formed using hafnium-containing crude zirconium as the anode, a nickel plate as the cathode, and a NaCl-KCl eutectic salt containing 10 wt% K2ZrF6 as the electrolyte; the hafnium content in the crude zirconium was 0.18 wt.%.

[0046] The electrolysis temperature was set to 750℃, and the current density was set to 0.25 A·cm. -2 Perform constant current electrolysis;

[0047] After electrolysis, the electrolysis products were collected, washed, and dried to obtain metallic zirconium particles with a hafnium content of 0.038 wt.%, as shown in the SEM image. Figure 1 As shown in (c).

[0048] Example 5

[0049] An electrolytic system was formed using hafnium-containing crude zirconium as the anode, a nickel plate as the cathode, and a NaCl-KCl eutectic salt containing 10 wt% K2ZrF6 as the electrolyte; the hafnium content in the crude zirconium was 0.18 wt.%.

[0050] The electrolysis temperature was set to 750℃, and the current density was set to 0.5 A·cm. -2 Perform constant current electrolysis;

[0051] After electrolysis, the electrolysis products were collected, washed, and dried to obtain dendritic metallic zirconium with a hafnium content of 0.047 wt.%. SEM images are shown below. Figure 1 As shown in (d).

[0052] Example 6

[0053] An electrolytic system was formed using hafnium-containing crude zirconium as the anode, a nickel plate as the cathode, and a NaCl-KCl eutectic salt containing 10 wt% K2ZrF6 as the electrolyte; the hafnium content in the crude zirconium was 0.18 wt.%.

[0054] The electrolysis temperature was set to 780℃, the pulse frequency of the pulse power supply was 80Hz, the duty cycle was 40%, and the peak current was set to 0.25A·cm. -2 Perform pulse electrolysis;

[0055] After electrolysis, the electrolysis products are collected, washed, and dried to obtain metallic zirconium particles, in which the hafnium content is 0.025 wt.%.

[0056] This invention discloses a method for preparing morphology-controllable metallic zirconium based on an active cathode. Utilizing a high-temperature molten salt electrolysis method, an active solid metal is used as the cathode. By controlling the electrolysis's power supply method and current density, and leveraging the dynamic dissolution-deposition of the active solid metal cathode material, precise control of the zirconium crystal morphology is achieved, avoiding the shortcomings of inert cathodes (such as molybdenum and tungsten) which cannot actively control zirconium crystallization behavior. Simultaneously, using an active solid metal as the electrode can improve the Zr / Hf separation coefficient, increase product purity, and reduce material costs and energy consumption. This method features a simple process flow, achieving separation and morphology control in a single step, is easy to operate, and does not generate harmful gases, showing promising application prospects in the nuclear industry, additive manufacturing, and other fields.

[0057] The technical solutions and technical details disclosed in the embodiments of this invention are merely illustrative of the inventive concept of this invention and do not constitute a limitation on the technical solutions of the embodiments of this invention. Any conventional changes, substitutions, or combinations made to the technical details disclosed in the embodiments of this invention have the same inventive concept as this invention and are within the protection scope of the claims of this invention.

Claims

1. A method for preparing morphology-controllable metallic zirconium based on active cathode modulation, characterized in that, include: An electrolysis system is constructed using crude zirconium metal as the anode, an active solid metal as the cathode, and a eutectic salt electrolyte containing K2ZrF6 as the molten salt electrolyte. Electrolysis was carried out under different electrolysis conditions, and high-purity zirconium with different morphologies was obtained on the cathode surface.

2. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 1, characterized in that, Electrolysis power supplies include constant current power supplies and pulse power supplies.

3. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 2, characterized in that, The current density of the constant current power supply is 0.01–10 A·cm. -2 .

4. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 2, characterized in that, The current density of the pulse power supply is 0.2–10 A·cm. -2 The pulse period of the pulse power supply is 2 to 20 minutes, and the duty cycle is 0.1 to 0.

9.

5. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 1, characterized in that, The electrolysis temperature is set to 450–850℃.

6. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 1, characterized in that, The eutectic salt electrolyte is a combination of at least two of LiCl, NaCl, and KCl, and the mass content of K2ZrF6 in the molten salt electrolyte is 1–20 wt.%.

7. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 1, characterized in that, The active solid metals include copper and nickel.

8. The method for preparing morphology-controllable metallic zirconium based on active cathode control according to claim 1, characterized in that, The crude metallic zirconium is a metallic zirconium containing metallic hafnium.

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