Fused salt electrolyte for metal production and method for its preparation
By heating molten chloride salt and chlorinating agent under vacuum or inert gas conditions, a low-valence metal ion electrolyte is generated, which solves the problem of high cost in the preparation of high-purity, high-melting-point metals, and realizes low-cost, large-scale production. It is suitable for electrolytic refining and purification of high-melting-point metals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN QINCHUANG HIGH PURITY NEW MATERIAL TECHNOLOGY CO LTD
- Filing Date
- 2026-03-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing methods for preparing high-purity, high-melting-point metals suffer from high production costs and the inability to produce continuously. In particular, the poor quality of raw materials makes it difficult to achieve large-scale, low-cost preparation in the electrolyte preparation process.
A method for preparing electrolytes using molten chloride salts involves heating a primary metal with a chlorinating agent under vacuum or inert gas conditions to generate a molten salt electrolyte containing low-valence metal ions. Chlorinating agents such as NH4Cl, HCl, CCl4, and Cl2 are used, and appropriate molten chloride salts such as LiCl, KCl, and NaCl are selected. The preparation process of the electrolyte is optimized by controlling the heating temperature and atmospheric conditions.
It reduces the cost of storage and reaction equipment for electrolyte preparation, realizes a highly efficient and inexpensive electrolyte preparation process, is suitable for the electrolytic refining and purification of high-melting-point metals, and improves the continuity and economy of production.
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Figure CN122147451A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of metal preparation technology, and more specifically, to a molten salt electrolyte for metal preparation and a method for preparing the same. Background Technology
[0002] High-purity, high-melting-point metals are widely used in high-end fields such as semiconductors, new energy, aerospace, biomedicine, and nuclear energy technology due to their extremely low impurity content and excellent physicochemical properties. Currently, mainstream methods for purifying high-purity, high-melting-point metals include vacuum distillation, electron beam melting, electrolytic refining, and directional solidification. However, methods such as vacuum distillation, electron beam melting, and directional solidification suffer from high production costs and the inability to produce continuously, severely restricting the widespread industrial production of high-purity, high-melting-point metals. Electrolytic refining technology, on the other hand, is considered a potential technology for low-cost preparation of high-purity, high-melting-point metals due to its advantages of continuous production and relatively low cost.
[0003] The preparation process of high-purity, high-melting-point metals based on molten salt electrolytic refining technology has been continuously explored and has made significant progress in recent years. Electrolyte preparation is a crucial step in the molten salt electrolytic refining process. Currently, the preparation of electrolytes faces challenges due to the high requirements for production equipment caused by poor-quality raw materials, making it difficult to achieve large-scale, low-cost electrolyte preparation.
[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0005] The purpose of this disclosure is to provide a molten salt electrolyte for metal preparation and a method for preparing the same, thereby overcoming, at least to some extent, the problem of high production costs for preparing electrolytes for metal preparation.
[0006] According to a first aspect of this disclosure, a method for preparing a molten salt electrolyte for metal preparation is provided, comprising: placing a primary metal and a chlorinating agent in a chloride molten salt, and heating the mixture under vacuum or inert gas conditions to obtain a molten salt electrolyte containing low-valence metal ions; wherein the purity of the primary metal is lower than the purity of the metal used to prepare the molten salt electrolyte; the primary metal, the metal corresponding to the low-valence metal ions, and the metal used to prepare the molten salt electrolyte are one of titanium, vanadium, hafnium, tantalum, zirconium, and chromium; and the chlorinating agent is one of NH4Cl, HCl, CCl4, and Cl2.
[0007] Optionally, the low-valence metal ion has a valence state of +2 or a mixed valence state of +2 and +3.
[0008] Optionally, the chloride molten salt is one of LiCl, KCl, NaCl, CsCl, NaCl-KCl, LiCl-KCl, LiCl-KCl-CsCl, NaCl-KCl-CsCl, NaCl-CsCl, MgCl2, and MgCl2-NaCl-KCl.
[0009] Optionally, the preparation method further includes: drying the original chloride salt in an oven; and heating the dried original chloride salt to a molten state to prepare a molten chloride salt.
[0010] Optionally, the drying temperature is 100~200℃.
[0011] Optionally, the preparation method further includes: after heating to a molten state, introducing HCl gas to remove impurities.
[0012] Optionally, the heating reaction under vacuum or inert gas conditions includes: heating the reaction at 250~1000°C for 30~1440 min under vacuum or inert gas conditions.
[0013] Optionally, the inert gas is one of argon, nitrogen, helium, or an argon-nitrogen mixture.
[0014] Optionally, the mass ratio of the original metal, chlorinating agent, and chloride molten salt is 1:(0.5~300):(5~300).
[0015] According to a second aspect of this disclosure, a molten salt electrolyte for metal preparation is provided, prepared using any of the above-described methods for preparing a molten salt electrolyte for metal preparation.
[0016] In the exemplary embodiments disclosed herein, the selected chlorinating agent exhibits low corrosivity and high stability, significantly reducing the cost of storage and reaction equipment. Furthermore, the electrolyte preparation process is simple, efficient, and inexpensive. This method directly generates low-valence, high-melting-point metal ions in molten chloride salts, making it suitable for the electrolytic refining and purification of high-melting-point metals.
[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description
[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.
[0019] Figure 1 A schematic diagram of the process for preparing molten salt electrolyte according to an embodiment of the present disclosure is shown.
[0020] Figure 2 A flowchart of a method for preparing molten salt electrolyte according to an embodiment of the present disclosure is shown.
[0021] Figure 3 A schematic diagram of the electrolyte containing low-valence titanium ions prepared according to Example 1 of this disclosure is shown.
[0022] Figure 4 The diagram illustrates the XRD (X-Ray Diffraction) pattern of high-purity titanium prepared in Example 2 of this disclosure.
[0023] Figure 5 The illustration shows an SEM (Scanning Electron Microscope) image of the high-purity titanium prepared in Example 2 of this disclosure. Detailed Implementation
[0024] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of these specific details omitted, or other methods, processes, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.
[0025] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. The flowcharts shown in the drawings are merely exemplary illustrations and do not necessarily include all steps. For example, some steps may be broken down, while others may be combined or partially combined; therefore, the actual order of execution may change depending on the specific circumstances.
[0026] For electrolytes used in the preparation of high-purity, high-melting-point metals, chloride molten salts can be used. Specifically, a high-valence, high-melting-point metal chloride and crude high-melting-point metal are added to generate low-valence metal ions, which are then used in subsequent electrolysis processes. However, high-valence, high-melting-point metal chlorides have disadvantages such as volatility, strong corrosiveness, poor stability, and high reactivity, placing higher demands on production equipment and making it difficult to achieve large-scale, low-cost electrolyte preparation.
[0027] To address or at least mitigate these problems, this disclosure provides a novel molten salt electrolyte and a method for its preparation.
[0028] refer to Figure 1 In an exemplary embodiment of this disclosure, the original metal and chlorinating agent can be placed in a chloride molten salt and heated under vacuum or inert gas conditions to obtain a molten salt electrolyte containing low-valence metal ions.
[0029] The purity of the primary metal is lower than that of the metal used in the molten salt electrolyte for preparation. The primary metal, the metal corresponding to the low-valence metal ion, and the metal used in the molten salt electrolyte for preparation are all selected from titanium, vanadium, hafnium, tantalum, zirconium, and chromium. The chlorinating agent is one of NH4Cl, HCl, CCl4, and Cl2.
[0030] Figure 2 A flowchart illustrating a method for preparing molten salt electrolytes according to embodiments of the present disclosure is shown. (Reference) Figure 2 The method for preparing molten salt electrolyte according to the present disclosure may include the following steps: S22. Place the original chloride salt in an oven for drying.
[0031] According to some embodiments of this disclosure, the drying temperature can be 100~200℃, and the drying time can be 27~72h.
[0032] S24. Heat the dried original chloride salt to a molten state to prepare a chloride molten salt.
[0033] According to some embodiments of this disclosure, HCl gas can be introduced after the heating process to a molten state to remove impurities.
[0034] Specifically, after drying, the original chloride salt can be transferred to a high-temperature heating device that is isolated from water and oxygen to melt it, and then HCl gas can be introduced for 0.5 to 24 hours. After cooling to room temperature, it can be crushed and reused.
[0035] The chloride molten salt in this embodiment can be one of LiCl, KCl, NaCl, CsCl, NaCl-KCl, LiCl-KCl, LiCl-KCl-CsCl, NaCl-KCl-CsCl, NaCl-CsCl, MgCl2, or MgCl2-NaCl-KCl. The "-" in NaCl-KCl represents a mixture of two or more compounds, and so on, without further elaboration.
[0036] S26. The original metal and chlorinating agent are placed in a chloride molten salt and heated under vacuum or inert gas conditions to obtain a molten salt electrolyte containing low-valence metal ions.
[0037] According to some embodiments of this disclosure, the mass ratio of the original metal, chlorinating agent, and chloride molten salt can be 1:(0.5~300):(5~300). A preferred ratio is 1:(5~20):(10~100).
[0038] In addition, the pressure under vacuum conditions is 1×10⁻⁶. -6 ~300Pa, preferably 1×10 -6 ~2Pa. The inert gas is one of argon, nitrogen, helium, or an argon-nitrogen mixture.
[0039] The reaction can be carried out under vacuum or inert gas conditions at 250~1000℃ for 30~1440 min. The heating rate is 1~10℃ / min.
[0040] For example, in the embodiments of this disclosure, a crucible can be used as a reaction vessel. The material of the crucible includes high-purity corundum, high-purity nickel, high-purity quartz, stainless steel, etc., with high-purity nickel crucibles being preferred.
[0041] According to some embodiments of this disclosure, the low-valence metal ions have a valence state of +2 or a mixed valence state of +2 and +3.
[0042] Furthermore, this disclosure also provides a molten salt electrolyte for metal preparation, prepared using the above-described preparation method.
[0043] The following describes Embodiment 1 of this disclosure.
[0044] The first step is to weigh 500g of a NaCl-KCl mixed salt (NaCl to KCl molar ratio of 1:1) and place it in a corundum crucible. Dry the crucible in a vacuum drying oven at 150℃ for 48 hours to remove moisture. Next, transfer the crucible to an argon atmosphere and heat it to 750℃ in a molten salt electrolysis furnace. After melting, HCl gas is introduced and maintained for 24 hours to thoroughly remove residual moisture and impurities. Then, cool to room temperature and crush the mixture into small pieces for later use.
[0045] The second step involves mixing 500g of NaCl-KCl molten salt obtained from the first step with 5.0g of metallic Ti and 2.0g of NH4Cl powder, then placing the mixture into an alumina crucible, transferring it into a molten salt electrolysis furnace, and introducing argon gas.
[0046] The third step involves heating to 800℃, then maintaining the temperature for 4 hours before cooling to obtain the following result: Figure 3 The image shows a molten salt electrolyte containing titanium ions.
[0047] The fourth step involves inserting a Ti plate as the cathode and sponge titanium as the anode, at a current of 0.1 A / cm. 2 After electrolysis with current for 3.5 hours, the cathode was lifted.
[0048] The fifth step involves washing the adhering salts in a 5% dilute hydrochloric acid solution with a solid-liquid ratio of 1:100, filtering, and then washing five times with deionized water with a solid-liquid ratio of 1:100. After that, the sample is placed in a vacuum drying oven at 150°C and dried for 4 hours to obtain a high-purity titanium sample.
[0049] Embodiment 2 of this disclosure will be described below.
[0050] First, weigh 500g of MgCl2 and place it in a corundum crucible. Dry it in a vacuum drying oven at 150℃ for 48 hours to remove moisture. Next, transfer it to an argon atmosphere and heat it to 750℃ in a molten salt electrolysis furnace. After melting, HCl gas is introduced and maintained for 24 hours to fully remove residual moisture and impurities. Then, cool it to room temperature and crush it into small pieces for later use.
[0051] The second step involves mixing 500g of MgCl2 molten salt obtained from the first step with 5.0g of metallic Ti and 2.0g of NH4Cl powder, then placing the mixture into an alumina crucible, transferring it into a molten salt electrolysis furnace, and introducing argon gas.
[0052] The third step involves heating the temperature to 700℃, then reacting at a constant temperature for 4 hours before cooling to obtain the molten salt electrolyte.
[0053] The fourth step involves using a molybdenum basket loaded with metallic Ti as the anode and a pure molybdenum rod as the cathode, with an anode of 0.1 A / cm. 2 After electrolysis at a current density for 4 hours, the electrodes were cooled and removed.
[0054] The fifth step involves washing the adhering salts in a 5% dilute hydrochloric acid solution with a solid-liquid ratio of 1:100 and then filtering. The solution is then washed five times with deionized water at a solid-liquid ratio of 1:100. After that, the solution is dried in a vacuum drying oven at 150°C for 4 hours to obtain the electrolytic product.
[0055] The electrolysis product was characterized by XRD and SEM, and the results are as follows: Figure 4 and Figure 5As shown in the figure. The results indicate that the prepared electrolytic product is high-purity Ti with a purity of 5N.
[0056] Embodiment 3 of this disclosure will be described below.
[0057] The first step is to weigh 500g of a NaCl-KCl mixed salt (NaCl to KCl molar ratio of 1:1) and place it in a corundum crucible. Dry the crucible in a vacuum drying oven at 150℃ for 48 hours to remove moisture. Next, transfer the crucible to an argon atmosphere and heat it to 750℃ in a molten salt electrolysis furnace. After melting, HCl gas is introduced and maintained for 24 hours to thoroughly remove residual moisture and impurities. Then, cool to room temperature and crush the mixture into small pieces for later use.
[0058] The second step involves mixing 500g of NaCl-KCl molten salt obtained from the first step with 5.0g of metallic V and 2.0g of NH4Cl powder, then placing the mixture into an alumina crucible, transferring it into a molten salt electrolysis furnace, and introducing argon gas.
[0059] The third step involves heating the temperature to 800℃, then reacting at a constant temperature for 4 hours before cooling to obtain the molten salt electrolyte.
[0060] The fourth step involves adding metal V to the molybdenum basket, inserting it into the molten salt as the anode, and simultaneously inserting a V plate as the cathode. A DC power supply of 0.5 A / cm is then connected. 2 After electrolysis at a current density for 4 hours, the cathode and anode electrodes were removed.
[0061] The fifth step involves washing the adhering salts in a 5% dilute hydrochloric acid solution with a solid-liquid ratio of 1:100, filtering the solution, and then washing it five times with deionized water with a solid-liquid ratio of 1:100. After that, the solution is placed in a vacuum drying oven at 150°C and dried for 4 hours to obtain the electrolysis product. GDMS (Glow Discharge Mass Spectrometry) results show that the purity of the electrolysis product reaches 5N.
[0062] Embodiment 4 of this disclosure will now be described.
[0063] The first step is to weigh 500g of a NaCl-KCl mixed salt (NaCl to KCl molar ratio of 1:1) and place it in a corundum crucible. Dry the crucible in a vacuum drying oven at 150℃ for 48 hours to remove moisture. Next, transfer the crucible to an argon atmosphere and heat it to 750℃ in a molten salt electrolysis furnace. After melting, HCl gas is introduced and maintained for 24 hours to thoroughly remove residual moisture and impurities. Then, cool to room temperature and crush the mixture into small pieces for later use.
[0064] The second step involves loading 500g of NaCl-KCl molten salt obtained from the first step into an alumina crucible, transferring it into a molten salt electrolysis furnace, and introducing argon gas.
[0065] The third step is to raise the temperature to 750℃, then place 10 g of metallic Ta in a molybdenum basket and put it into the molten salt, and continuously introduce HCl gas into the molten salt at a flow rate of 5 g / h for 6 hours.
[0066] Fourth step: After the reaction is complete, lift the molybdenum basket, stop the HCl gas flow, insert the Ta plate as the anode and the Ta rod as the cathode, and connect a DC power supply at 0.2 A / cm. 2 After electrolysis at a current density for 10 hours, the cathode and anode electrodes were lifted and the cathode product was collected.
[0067] The fifth step involves washing the adhering salts in a 5% dilute hydrochloric acid solution with a solid-liquid ratio of 1:100 and then filtering. The solution is then washed five times with deionized water at a solid-liquid ratio of 1:100. After drying in a vacuum drying oven at 150°C for 4 hours, the electrolytic product is obtained. GDMS results show that the purity of the electrolytic product reaches 5N.
[0068] Embodiment 5 of this disclosure will now be described.
[0069] The first step is to weigh 500g of a NaCl-KCl mixed salt (NaCl to KCl molar ratio of 1:1) and place it in a corundum crucible. Dry the crucible in a vacuum drying oven at 150℃ for 48 hours to remove moisture. Next, transfer the crucible to an argon atmosphere and heat it to 750℃ in a molten salt electrolysis furnace. After melting, HCl gas is introduced and maintained for 24 hours to thoroughly remove residual moisture and impurities. Then, cool to room temperature and crush the mixture into small pieces for later use.
[0070] The second step involves loading 500g of NaCl-KCl molten salt obtained from the first step into an alumina crucible, transferring it into a molten salt electrolysis furnace, and introducing argon gas.
[0071] The third step is to raise the temperature to 800℃, then place 10 g of metallic Zr in a molybdenum basket and put it into the molten salt, and continuously introduce HCl gas into the molten salt at a flow rate of 5 g / h for 6 hours.
[0072] Fourth step: After the reaction is complete, lift the molybdenum basket, stop the HCl gas flow, insert a Zr plate as the anode and a Zr rod as the cathode, and connect a DC power supply at 0.2 A / cm. 2 After electrolysis at a current density for 10 hours, the cathode and anode electrodes were lifted and the cathode product was collected.
[0073] The fifth step involves washing the adhering salts in a 5% dilute hydrochloric acid solution with a solid-liquid ratio of 1:100 and then filtering. The solution is then washed five times with deionized water at a solid-liquid ratio of 1:100. After drying in a vacuum drying oven at 150°C for 4 hours, the electrolytic product is obtained. GDMS results show that the purity of the electrolytic product reaches 5N.
[0074] Embodiment 6 of this disclosure will now be described.
[0075] The first step involves weighing 500g of a LiCl-KCl mixed salt (LiCl to KCl mass ratio of 44:56) and placing it in a corundum crucible. The crucible is then dried in a vacuum drying oven at 150℃ for 48 hours to remove moisture. Next, the mixture is transferred to an argon atmosphere and heated to 750℃ in a molten salt electrolysis furnace. After melting, HCl gas is introduced and maintained for 24 hours to thoroughly remove residual moisture and impurities. Finally, the mixture is cooled to room temperature and pulverized into small pieces for later use.
[0076] The second step involves placing 500g of LiCl-KCl molten salt obtained from the first step and 5.0g of metallic Cr into a corundum crucible, transferring it into a molten salt electrolysis furnace, and introducing argon gas.
[0077] The third step is to raise the temperature to 500℃ and continuously introduce HCl gas into the molten salt at a flow rate of 5g / h for 6 hours.
[0078] Fourth step: After the reaction is complete, lift the molybdenum basket, stop the HCl gas flow, insert a Cr plate as the anode and a Ni rod as the cathode, and connect a DC power supply at 0.2 A / cm. 2 After electrolysis at a current density for 20 hours, the cathode and anode electrodes were lifted and the cathode product was collected.
[0079] The fifth step involves washing the adhering salts in a 5% dilute hydrochloric acid solution with a solid-liquid ratio of 1:20 and then filtering. The solution is then washed five times with deionized water at a solid-liquid ratio of 1:20. After drying in a vacuum drying oven at 80°C for 6 hours, the electrolytic product is obtained. GDMS results show that the purity of the electrolytic product reaches 4N5.
[0080] It should be noted that although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.
[0081] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this disclosure and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.
[0082] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.
[0083] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.
Claims
1. A method for preparing a molten salt electrolyte for metal preparation, characterized in that, include: The original metal and chlorinating agent are placed in a chloride molten salt and heated under vacuum or inert gas conditions to obtain a molten salt electrolyte containing low-valence metal ions. Wherein, the purity of the original metal is lower than the purity of the metal used to prepare the molten salt electrolyte; the original metal, the metal corresponding to the low-valence metal ion, and the metal used to prepare the molten salt electrolyte are one of titanium, vanadium, hafnium, tantalum, zirconium, and chromium; the chlorinating agent is one of NH4Cl, HCl, CCl4, and Cl2.
2. The preparation method according to claim 1, characterized in that, The low-valence metal ions are in the valence state of +2 or a mixture of +2 and +3.
3. The preparation method according to claim 1, wherein the chloride molten salt is one of LiCl, KCl, NaCl, CsCl, NaCl-KCl, LiCl-KCl, LiCl-KCl-CsCl, NaCl-KCl-CsCl, NaCl-CsCl, MgCl2, and MgCl2-NaCl-KCl.
4. The preparation method according to claim 3, characterized in that, The preparation method further includes: The original chloride salt was placed in an oven for drying. The original chloride salt, after being dried, is heated to a molten state to prepare the chloride molten salt.
5. The preparation method according to claim 4, characterized in that, The drying temperature is 100~200℃.
6. The preparation method according to claim 4, characterized in that, The preparation method further includes: After heating to a molten state, HCl gas is introduced to remove impurities.
7. The preparation method according to claim 1, characterized in that, Heating reactions under vacuum or inert gas conditions include: The reaction is carried out under vacuum or inert gas conditions at 250-1000℃ for 30-1440 min.
8. The preparation method according to claim 1, characterized in that, The inert gas is one of argon, nitrogen, helium, or an argon-nitrogen mixture.
9. The preparation method according to claim 1, characterized in that, The mass ratio of the original metal, the chlorinating agent, and the chloride molten salt is 1:(0.5~300):(5~300).
10. A molten salt electrolyte for metal preparation, characterized in that, It is prepared using the method for preparing molten salt electrolytes for metal preparation as described in any one of claims 1 to 9.