Cathode for rare earth molten salt electrolysis and electrolysis system comprising same
By optimizing the columnar or conical cathode design, the problem of high current density in the electrolysis of rare earth fluoride molten salts is solved, and the efficient electrolysis and high yield of rare earth metals are achieved, thereby reducing greenhouse gas emissions.
Patent Information
- Application Number
- CN202311861850.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-07-01
AI Technical Summary
In the process of electrolysis of rare earth fluoride molten salts, fluorine gas/fluorocarbons may be generated under high anode current density, resulting in greenhouse gas emissions. The existing electrode structure fails to effectively reduce the cathode local current density, affecting the yield of rare earth metals.
The cathode design is adopted, with sharp angles or flat tops of the cathode, and the surface area ratio between the cathode and the anode is between 1:100 and 1:1. Using tungsten, molybdenum or tantalum materials, the local current density is reduced by adjusting the electrode shape and size, and the metal droplet collection efficiency is improved.
By optimizing the electrode design, it reduces metal oxidation, improves the electrolytic efficiency and yield of rare earth metals, reduces the anode current density, avoids the decomposition of fluorine salt electrolytes, and improves the metal deposition aggregation effect.
Smart Images
Figure CN120231098A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a cathode and an electrolysis system including the same, and particularly to a cathode for rare earth molten salt electrolysis and an electrolysis system including the same. Background Art
[0002] Rare earth elements have a crucial impact on improving product performance and are widely used in applications such as permanent magnets, ceramics and glass, optoelectronics, catalytic raw materials, superconductivity, and green energy. However, in the rare earth fluoride molten salt electrolysis process, in addition to carbon monoxide and carbon dioxide, fluorine gas / fluorocarbides may be generated at high anode current densities, resulting in greenhouse gas emissions. Therefore, it is necessary to reduce the local cathode current density and the anode current density through the electrode structure in the molten salt electrolysis process and the electrode arrangement of the electrolysis system to improve the rare earth metal yield. Summary of the Invention
[0003] According to an embodiment of the present disclosure, there is provided a cathode for preparing rare earth metals by rare earth molten salt electrolysis, including: a columnar body, the bottom of the columnar body includes a conical shape, and the top of the conical shape includes a sharp angle or a flat surface; wherein when the top of the conical shape is a sharp angle, the sharp angle is between 5 degrees and 175 degrees.
[0004] In one embodiment, the cathode is composed of tungsten, molybdenum, or tantalum.
[0005] In one embodiment, when the lengths of the sides of the conical shape are the same, the angle of the sharp angle is obtained by formula (I): c 2 = 2a 2 (1 - cos(γ)), in formula (I), c is the diameter of the columnar body, a is the length of the side of the conical shape, and γ is the angle of the sharp angle. In one embodiment, the lengths of the sides of the conical shape are different.
[0006] According to an embodiment of the present disclosure, there is provided an electrolysis system, including: a cathode; at least one anode; and an electrolyte containing rare earth oxides, wherein the cathode and the anode are placed in the electrolyte. The ratio of the surface area of the cathode to the surface area of the anode is between 1:100 and 1:1.
[0007] In one embodiment, the cathode includes a columnar body. In one embodiment, the bottom of the cathode includes a flat surface, an arc shape, or a conical shape.
[0008] In one embodiment, the top of the conical shape includes a sharp angle or a flat surface. In one embodiment, when the top of the conical shape is a sharp angle, the angle of the sharp angle is between 5 degrees and 175 degrees. In one embodiment, when the top of the conical shape is a sharp angle and the lengths of the sides of the conical shape are the same, the angle of the sharp angle is obtained by formula (I): c 2 = 2a 2(1 - cos(γ)), where in formula (I), c is the diameter of the cylinder, a is the length of the conical side, and γ is the angle of the sharp corner. In one embodiment, the tip of the cone is a sharp corner and the lengths of the conical sides are different.
[0009] In one embodiment, at least one anode surrounds the cathode.
[0010] In one embodiment, the cathode is composed of tungsten, molybdenum, or tantalum. In one embodiment, at least one anode is composed of graphite.
[0011] In one embodiment, the rare earth oxides include neodymium oxide, praseodymium oxide, or dysprosium oxide.
[0012] The present disclosure uses a fluoride system / rare earth molten salt electrolyte system, with the anode being graphite, the cathode being tungsten, molybdenum, or tantalum and having a columnar, conical, or combined shape. The cathode is placed at the center of the crucible, and the anode is located around or symmetrically to the cathode. After passing an electric current, an electrolysis reaction is carried out. During the electrolysis process, since the melting point of the generated rare earth metal is lower than that of the cathode, the surface layer of the cathode is first electrolyzed into metal droplets, which fall into the crucible at the bottom.
[0013] When the particle size of the obtained rare earth metal becomes larger, the specific surface area decreases proportionally. This phenomenon can significantly reduce metal oxidation and improve the electrolysis efficiency.
[0014] The size and shape of the cathode will affect the local current density, causing the reduced metal to form droplets of different sizes. For example, at the tip of the electrode, there will be current concentration and an increase in the local current density under the condition of providing the same current density. This will increase the amount of metal electrolytically deposited, increase the diameter of the metal droplets, make the metal droplets easier to collect, and achieve high electrolysis efficiency.
[0015] The main technology of the present disclosure is to utilize the electrolysis electrode design in the metal electrolysis system containing fluoride molten salt to improve the recovery rate of electrolytic metal and reduce the anode current density, avoid the decomposition of fluoride salt electrolyte to generate fluorine gas / fluoride, deposit and aggregate rare earth metals, and improve the metal yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1A is a schematic diagram of an electrolysis system according to an embodiment of the present disclosure;
[0017] Figure 1B is a schematic diagram of an electrolysis system according to an embodiment of the present disclosure;
[0018] Figure 2A is a cross-sectional schematic diagram of the cathode structure in an electrolysis system according to an embodiment of the present disclosure;
[0019] Figure 2BIt is a schematic cross-sectional view of a cathode structure in an electrolysis system according to an embodiment of the present disclosure;
[0020] Figure 2C It is a schematic cross-sectional view of a cathode structure in an electrolysis system according to an embodiment of the present disclosure;
[0021] Figure 2D It is a schematic cross-sectional view of a cathode structure in an electrolysis system according to an embodiment of the present disclosure;
[0022] Figure 3 It is a graph showing the relationship between the particle size of the product and the current efficiency obtained from different electrolysis systems according to an embodiment of the present disclosure.
[0023] Symbol Explanation
[0024] 10: Electrolysis system
[0025] 12: Cathode
[0026] 12 B : Bottom of the cathode
[0027] 12 Bb : Top of the bottom of the cathode
[0028] 14: Anode
[0029] 12 B ’: 12 B ”: Side of the bottom of the cathode
[0030] a, b: Lengths of the sides of the bottom of the cathode
[0031] C: Diameter of the cathode
[0032] γ: Angle of the sharp corner Detailed Embodiments
[0033] The following disclosure provides many different embodiments for implementing different features of the present application.
[0034] In the specification, terms such as "about", "approximately", "substantially", "roughly", "essentially", "the same", "similar" generally indicate a range within plus or minus 15%, or plus or minus 10%, or plus or minus 5%, or plus or minus 3%, or plus or minus 2%, or plus or minus 1%, or plus or minus 0.5% of a given value of a feature. The given quantity is an approximate quantity, and thus the meaning of "about", "approximately", "substantially", "roughly", "essentially" may still be implied even without specific mention of "about", "approximately", "substantially", "roughly", "essentially".
[0035] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It is understood that these terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with the relevant technology and the background or context of the present invention, and should not be interpreted in an idealized or overly formal manner, unless specifically defined in the embodiments of the present invention.
[0036] Please refer to Figure 1A , according to an embodiment of the present disclosure, an electrolysis system 10 is provided. Figure 1A is a schematic diagram of the electrolysis system 10.
[0037] As Figure 1A shown, the electrolysis system 10 includes a cathode 12, an anode 14, and an electrolyte (not shown). The cathode 12 is composed of tungsten, molybdenum, or tantalum. The anode 14 is composed of graphite. The electrolyte contains rare earth oxides. The cathode 12 and the anode 14 are placed in the electrolyte. The ratio of the surface area of the cathode 12 to the surface area of the anode 14 is between 1:100 and 1:1.
[0038] Please refer to Figure 1B , according to an embodiment of the present disclosure, an electrolysis system 10 is provided. Figure 1B is a schematic diagram of the electrolysis system 10.
[0039] As Figure 1B shown, the electrolysis system 10 includes a cathode 12, a plurality of anodes 14, and an electrolyte (not shown). The cathode 12 is composed of tungsten, molybdenum, or tantalum. The anode 14 is composed of graphite and surrounds the cathode 12. The electrolyte contains rare earth oxides. The cathode 12 and the anode 14 are placed in the electrolyte. The ratio of the surface area of the cathode 12 to the surface area of the anode 14 is between 1:100 and 1:1.
[0040] Please refer to Figures 2A to 2D , according to an embodiment of the present disclosure, the shape of the cathode 12 in the electrolysis system 10 is further described. Figures 2A to 2D is a cross-sectional schematic diagram of the cathode 12.
[0041] As Figure 2A shown, in one embodiment, the cathode 12 is a cylinder, and the bottom 12 of the cathode 12 B is a plane.
[0042] As Figure 2B shown, in one embodiment, the cathode 12 is a cylinder, and the bottom 12 of the cathode 12 B is arc-shaped.
[0043] As Figure 2CAs shown, in one embodiment, the cathode 12 is a column, and the bottom 12 of the cathode 12 B The cone-shaped bottom 12 B The top 12 Bb For sharp corners.
[0044] like Figure 2C As shown, in one embodiment, when the bottom 12 of the cathode 12 B The top 12 Bb When the tip is a sharp angle, the angle γ of the sharp angle is greater than 0 degrees and less than 180 degrees, for example, between 5 degrees and 175 degrees. B The top 12 Bb The cone bottom is 12 B Side 12 B 'The length a and the side 12 B When the length b of " is the same, the angle γ of the sharp corner is calculated by the following formula (I).
[0045] c 2 =2a 2 (1-cos(γ))(I)
[0046] In formula (I), c is the diameter of the cathode 12, and a is the diameter of the conical bottom 12. B Side 12 B ', and γ is the angle of the sharp corner.
[0047] In one embodiment, the bottom 12 of the cathode 12 B The top 12 Bb The cone bottom is 12 B Side 12 B 'The length a and the side 12 B The length b of " is different (not shown).
[0048] like Figure 2D As shown, the cathode 12 is a column, and the bottom 12 of the cathode 12 B The cone-shaped bottom 12 B The top 12 Bb For flat.
[0049] The shape of the cathode 12 of the present disclosure is not limited to Figures 2A to 2D The shapes shown, other suitable cylindrical, conical, or combination thereof structures are also applicable to the present disclosure.
[0050] In one embodiment, the rare earth oxide in the electrolyte includes neodymium oxide, praseodymium oxide, or dysprosium oxide.
[0051] Example
[0052] Add rare earth oxides (e.g., neodymium oxide (Nd₂O₃)) to an electrolyte containing rare earth fluorides (e.g., neodymium fluoride (NdF₃)) and lithium fluoride (LiF), and place the above electrolyte in a graphite crucible. Then, transfer the graphite crucible into a metal cavity that can be hermetically filled with an inert gas for protection, heat the temperature to above 1,050 °C, use graphite as the anode and tungsten as the cathode for electrolysis, and neodymium metal can be obtained on the tungsten electrode or in the electrolyte.
[0053] Example 1
[0054] Prepare neodymium metal using the electrolysis system of the present disclosure (cathode: columnar structure, bottom is flat)
[0055] Add neodymium oxide (1.5 wt%) to an electrolyte containing 90% neodymium fluoride and 10% lithium fluoride, and place the above electrolyte in a graphite crucible. Then, transfer the graphite crucible into a metal cavity that can be hermetically filled with an inert gas (Ar) for protection, heat the temperature to 1050 °C, use graphite as the anode and tungsten as the cathode for electrolysis, and neodymium metal can be obtained on the tungsten electrode or in the electrolyte.
[0056] The diameter of the anode is 10 mm and the length is 150 mm. The diameter of the cathode is 10 mm and the length is 150 mm. The cathode is a columnar structure with a flat bottom. The ratio of the surface area of the cathode to the surface area of the anode is 1:1. The depth at which the electrodes are immersed in the electrolyte is 50 mm. The current density is 150 ASD. The electrolysis time is 2 hours. The tungsten electrode diameter, the maximum particle size of the product, and the specific surface area are listed in Table 1 below.
[0057] Table 1
[0058] Tungsten electrode diameter (mm) Maximum particle size of product (mm) <![CDATA[Specific surface area (cm 2 / g)]]> 10 6～7 0.69～1.01
[0059] According to Table 1, after the electrolysis reaction is carried out using the electrolysis system of this example (cathode: columnar structure, bottom is flat, diameter is 10 mm), the maximum particle size of the obtained neodymium metal is between approximately 6 mm and approximately 7 mm, and its specific surface area is between approximately 0.69 cm 2 / g and approximately 1.01 cm 2 / g.
[0060] Example 2
[0061] Prepare neodymium metal using the electrolysis system of the present disclosure (cathode: columnar structure, bottom is flat)
[0062] Add neodymium oxide (1.5 wt%) to an electrolyte containing 90% neodymium fluoride and 10% lithium fluoride, and place the above electrolyte in a graphite crucible. Then, transfer the graphite crucible into a metal cavity that can be hermetically filled with an inert gas (Ar) for protection, heat the temperature to 1050 °C, use graphite as the anode and tungsten as the cathode for electrolysis, and neodymium metal can be obtained on the tungsten electrode or in the electrolyte.
[0063] The diameter of the anode is 10 mm and the length is 150 mm. The diameter of the cathode is 3.2 mm and the length is 150 mm. The cathode is a columnar structure with a flat bottom. The ratio of the surface area of the cathode to the surface area of the anode is 1:3.16. The depth at which the electrodes are immersed in the electrolyte is 50 mm. The current density is 150 ASD. The electrolysis time is 2 hours. The tungsten electrode diameter, the maximum particle size of the product, and the specific surface area are listed in Table 2 below.
[0064] Table 2
[0065] Tungsten electrode diameter (mm) Maximum particle size of product (mm) <![CDATA[Specific surface area (cm 2 / g)]]> 3.2 15～16 0.48～0.51
[0066] According to Table 2, after the electrolysis reaction is carried out by the electrolysis system of this example (cathode: columnar structure, flat bottom, diameter 3.2 mm), the maximum particle size of the obtained neodymium metal is between about 15 mm and about 16 mm, and its specific surface area is between about 0.48 cm 2 / g and about 0.51 cm 2 / g.
[0067] From the results shown in Table 1 and Table 2, it can be seen that when the diameter of the tungsten electrode in the electrolysis system is reduced from 10 mm to 3.2 mm, the maximum particle size of the obtained neodymium metal becomes significantly larger and the specific surface area becomes significantly smaller, which will help reduce the oxidation of neodymium metal and improve the electrolysis efficiency.
[0068] Example 3
[0069] Prepare neodymium metal using the electrolysis system of the present disclosure (cathode: combined columnar and conical structure, tip at the bottom)
[0070] Add neodymium oxide (1.5 wt%) to an electrolyte containing 90% neodymium fluoride and 10% lithium fluoride, and place the above electrolyte in a graphite crucible. Then, transfer the graphite crucible into a metal cavity that can be hermetically filled with an inert gas (Ar) for protection, heat the temperature to 1050 °C, use graphite as the anode and tungsten as the cathode for electrolysis, and neodymium metal can be obtained on the tungsten electrode or in the electrolyte.
[0071] The diameter of the anode is 10 mm and the length is 150 mm. The diameter of the cathode is 3.2 mm and the length is 150 mm. The cathode is a columnar structure with a tip at the bottom, and the cone angle is obtained from formula (I). The ratio of the surface area of the cathode to the surface area of the anode is 1:3.42. The depth at which the electrodes are immersed in the electrolyte is 50 mm. The current density is 150 ASD. The electrolysis time is 2 hours. The tungsten electrode diameter, the maximum particle size of the product, and the specific surface area are listed in Table 3 below.
[0072] Table 3
[0073]
[0074]
[0075] According to Table 3, after electrolysis with the electrolysis system of this example (cathode: combined columnar and conical structure, tip at the bottom, diameter 3.2 mm), the maximum particle size of the obtained neodymium metal is between approximately 16 mm and approximately 18 mm, and its specific surface area is between approximately 0.37 cm 2 / g and approximately 0.48 cm 2 / g.
[0076] From the results shown in Table 2 and Table 3, it can be seen that when the bottom structure of the tungsten electrode in the electrolysis system is changed from a plane to a tip, due to the phenomenon of current concentration and increased local current density that can occur at the electrode tip, the diameter of the obtained metal droplets can be further increased and the specific surface area can be further reduced. In this way, the amount of metal deposited by electrolysis can be increased, and it is easier to collect the metal droplets, achieving high electrolysis efficiency.
[0077] Example 4
[0078] Preparation of neodymium metal using the electrolysis system of the present disclosure (cathode: columnar structure, bottom is a plane)
[0079] Neodymium oxide (2.0 wt%) is added to an electrolyte containing 76% neodymium fluoride, 20% lithium fluoride, and 4% barium fluoride, and the above electrolyte is placed in a graphite crucible. Then, the graphite crucible is transferred into a metal cavity that can be hermetically filled with an inert gas (Ar) for protection, and the heating temperature is raised to 1050 °C. Using graphite as the anode and tungsten as the cathode, electrolysis is carried out, and neodymium metal can be obtained on the tungsten electrode or in the electrolyte.
[0080] The diameter of the anode is 10 mm and the length is 150 mm. The diameter of the cathode is 6.5 mm and the length is 150 mm. The cathode is a columnar structure with a plane at the bottom. The ratio of the surface area of the cathode to the surface area of the anode is 1:1.58. The depth at which the electrodes are immersed in the electrolyte is 30 mm. The current density is 120 ASD. The electrolysis time is 2 hours. The tungsten electrode diameter, the maximum particle size of the product, and the specific surface area are listed in Table 4 below.
[0081] Table 4
[0082] Tungsten electrode diameter (mm) Maximum particle size of product (mm) <![CDATA[Specific surface area (cm 2 / g)]]> 6.5 7～9 0.96～1.24
[0083] According to Table 4, after the electrolysis reaction was carried out by the electrolysis system of this embodiment (cathode: columnar structure, bottom is flat, diameter 6.5 mm), the maximum particle size of the obtained neodymium metal was between about 7 mm and about 9 mm, and its specific surface area was between about 0.96 cm 2 / g and about 1.24 cm 2 / g.
[0084] Example 5
[0085] Preparation of neodymium metal using the electrolysis system of the present disclosure (cathode: columnar structure, bottom is flat)
[0086] Neodymium oxide (2.0 wt%) was added to an electrolyte containing 76% neodymium fluoride, 20% lithium fluoride, and 4% barium fluoride, and the above electrolyte was placed in a graphite crucible. Then, the graphite crucible was transferred into a metal cavity that could be hermetically filled with an inert gas (Ar) for protection, and the heating temperature was raised to 1050 °C. Using graphite as the anode and tungsten as the cathode, electrolysis was carried out, and neodymium metal could be obtained on the tungsten electrode or in the electrolyte.
[0087] The diameter of the anode was 10 mm and the length was 150 mm. The diameter of the cathode was 3.2 mm and the length was 150 mm. The cathode was a columnar structure with a flat bottom. The ratio of the surface area of the cathode to the surface area of the anode was 1:3.29. The depth at which the electrode was immersed in the electrolyte was 30 mm. The current density was 120 ASD. The electrolysis time was 2 hours. The tungsten electrode diameter, the maximum particle size of the product, and the specific surface area are listed in Table 5 below.
[0088] Table 5
[0089] Tungsten electrode diameter (mm) Maximum particle size of product (mm) <![CDATA[Specific surface area (cm 2 / g)]]> 3.2 14～15 0.58～0.62
[0090] According to Table 5, after the electrolysis reaction was carried out by the electrolysis system of this embodiment (cathode: columnar structure, bottom is flat, diameter 3.2 mm), the maximum particle size of the obtained neodymium metal was between about 14 mm and about 15 mm, and its specific surface area was between about 0.58 cm 2 / g and about 0.62 cm 2 / g.
[0091] As can be seen from the results shown in Table 4 and Table 5, when we adjusted the electrolyte composition (for example, adding barium fluoride), if the diameter of the tungsten electrode continued to shrink from 6.5 mm to 3.2 mm at this time, the maximum particle size of the obtained neodymium metal would still increase and the specific surface area would still decrease. That is, during the electrolysis process, adjusting the electrolyte composition has less impact on the electrolysis efficiency, and the cathode size should be one of the important key factors for further improving the electrolysis efficiency.
[0092] Example 6
[0093] Relationship between particle size of products and current efficiency obtained from different electrolysis systems (different cathode sizes and shapes)
[0094] In this example, electrolysis reactions were carried out using different electrolysis systems (I, II, III, IV), and the relationship between the particle size of the obtained products and the current efficiency is shown in Table 6 below and Figure 3 。 Figure 3 is a graph showing the relationship between the particle size of products and the current efficiency obtained from different electrolysis systems.
[0095] Electrolysis system I: The electrolysis system as shown in Example 1 (cathode: columnar structure, bottom is flat, diameter 10 mm).
[0096] Electrolysis system II: The electrolysis system as shown in Example 4 (cathode: columnar structure, bottom is flat, diameter 6.5 mm).
[0097] Electrolysis system III: The electrolysis system as shown in Example 5 (cathode: columnar structure, bottom is flat, diameter 3.2 mm).
[0098] Electrolysis system IV: The electrolysis system as shown in Example 3 (cathode: combined columnar and conical structure, bottom is a tip, diameter 3.2 mm).
[0099] Table 6
[0100] Cathode diameter (mm) Particle size of product (mm) Current efficiency (%) 10 (bottom is flat) 6 47.4 6.5 (bottom is flat) 8 50 3.2 (bottom is flat) 14 51 3.2 (bottom is pointed) 16 71
[0101] As can be seen from the results shown in Table 6 and Figure 3 shown, as the diameter of the tungsten electrode shrank from 10 mm to 3.2 mm, the particle size of the obtained neodymium metal gradually increased (6 mm, 8 mm, 14 mm), and the current efficiency gradually increased (47.4%, 50%, 51%). When the bottom structure of the tungsten electrode changed from flat (as shown in electrolysis system III) to a tip (as shown in electrolysis system IV), the diameter of the obtained metal droplets could be further increased to 16 mm, and the current efficiency could be further increased to 71%.
[0102] The present disclosure uses a fluoride system / rare earth molten salt electrolyte system, with a graphite anode, a cathode made of tungsten, molybdenum, or tantalum and in the shape of a column, a cone, or a combination thereof. The cathode is placed at the center of the crucible, and the anode is located around the cathode or at a symmetric position. After current is passed through, an electrolysis reaction is carried out. During the electrolysis process, since the melting point of the generated rare earth metal is lower than that of the cathode, the surface layer of the cathode is first electrolyzed into metal droplets, which fall into the crucible at the bottom.
[0103] The size and shape of the cathode will affect the local current density, causing the reduced metal to form droplets of different sizes. For example, at the tip of the electrode, current concentration occurs under the same provided current density, increasing the local current density. This will increase the amount of metal electrolytically deposited, increase the diameter of the metal droplets, making the metal droplets easier to collect and achieving high electrolysis efficiency.
[0104] When the particle size of the obtained rare earth metal becomes larger, the specific surface area decreases proportionally. This phenomenon can significantly reduce metal oxidation and improve the electrolysis efficiency.
[0105] The main technology of the present disclosure is to utilize the electrolysis electrode design in the metal electrolysis system with fluoride molten salt to improve the recovery rate of electrolytic metal and reduce the anode current density, avoid the decomposition of fluoride electrolyte to generate fluorine / fluorides, deposit and aggregate rare earth metals, and increase the metal yield.
[0106] The above-mentioned some embodiments are provided so that those with ordinary knowledge in the technical field to which the present invention pertains can better understand the viewpoints of the implementation schemes of the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains should understand that they can design or modify other processes and compositions based on the embodiments of the present invention to achieve the same purpose and / or advantages as the embodiments introduced herein. Those with ordinary knowledge in the technical field to which the present invention pertains should also understand that such similar processes and compositions do not depart from the spirit and scope of the present invention, and they can make various changes, substitutions, and replacements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by what is defined in the appended claims. Additionally, although the present invention has been disclosed above with several preferred embodiments, it is not intended to limit the present invention.
[0107] The reference throughout the specification to features, advantages, or similar language does not imply that all features and advantages achievable by the present invention should or can be achieved in any single embodiment of the present invention. On the contrary, language referring to features and advantages is understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the discussion of features and advantages and similar language throughout the specification may, but does not necessarily, refer to the same embodiment.
[0108] Moreover, in one or more embodiments, the described features, advantages, and characteristics of the present invention may be combined in any suitable manner. Based on the description herein, those skilled in the relevant art will recognize that the present invention can be implemented without one or more specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be discerned in certain embodiments that may not be present in all embodiments of the present invention.
Claims
1. A cathode for rare earth molten salt electrolysis, comprising: A cylinder, the bottom of the cylinder includes a cone shape, and the top of the cone shape includes a sharp angle or a flat surface; Wherein when the top of the cone shape is a sharp angle, the angle of the sharp angle is between 5 degrees and 175 degrees.
2. The cathode for rare earth molten salt electrolysis according to claim 1, wherein the cathode is composed of tungsten, molybdenum, or tantalum.
3. The cathode for rare earth molten salt electrolysis according to claim 1, wherein when the lengths of the sides of the cone shape are the same, the angle of the sharp angle is obtained by formula (I): c 2 = 2a 2 (1 - cos(γ))(I), Where c is the diameter of the cylinder, a is the length of the side of the cone shape, and γ is the angle of the sharp angle.
4. The cathode for rare earth molten salt electrolysis according to claim 1, wherein the lengths of the sides of the cone shape are different.
5. An electrolysis system, comprising: A cathode; At least one anode; And An electrolyte containing rare earth oxides, Wherein the cathode and the at least one anode are placed in the electrolyte, and Wherein the ratio of the surface area of the cathode to the surface area of the at least one anode is between 1:100 and 1:
1.
6. The electrolysis system according to claim 5, wherein the cathode includes a cylinder.
7. The electrolysis system according to claim 6, wherein the bottom of the cathode includes a flat surface, an arc shape, or a cone shape.
8. The electrolysis system according to claim 7, wherein the top of the cone shape includes a sharp angle or a flat surface.
9. The electrolysis system according to claim 8, wherein when the top of the cone shape is a sharp angle, the angle of the sharp angle is between 5 degrees and 175 degrees.
10. The electrolysis system according to claim 8, wherein when the top of the cone shape is a sharp angle and the lengths of the sides of the cone shape are the same, the angle of the sharp angle is obtained by formula (I): c 2 = 2a 2 (1 - cos(γ))(I), Where c is the diameter of the cylinder, a is the length of the side of the cone shape, and γ is the angle of the sharp angle.
11. The electrolysis system according to claim 8, wherein the top of the cone shape is a sharp angle and the lengths of the sides of the cone shape are different.
12. The electrolysis system according to claim 5, wherein the at least one anode surrounds the cathode.
13. The electrolysis system according to claim 5, wherein the cathode is composed of tungsten, molybdenum, or tantalum.
14. The electrolysis system according to claim 5, wherein the at least one anode is composed of graphite.
15. The electrolysis system according to claim 5, wherein the rare earth oxides include neodymium oxide, praseodymium oxide, or dysprosium oxide.