Hydrated molten salt feeding device and system for preparing rare earth metal by electrolysis

Abstract

The utility model discloses a kind of hydrated molten salt feeding devices and the system of electrolytic preparation rare earth metal.The hydrated molten salt feeding device includes: melting unit, the melting unit includes melting chamber, and the melting chamber is used to accommodate hydrated salt;Heating unit, the heating unit includes waste heat collection mechanism, heat conduction heating mechanism, circulating pipeline, heat-conducting fluid medium and circulating pump, the waste heat collection mechanism, the heat conduction heating mechanism is communicated through the circulating pipeline, and forms a closed loop, and the heat-conducting fluid medium is filled in the closed loop;Material conveying unit, the material conveying unit is connected with the melting chamber, and is used to transport hydrated molten salt in the melting chamber to electrolytic device.The hydrated molten salt feeding device provided by the utility model heats hydrated molten salt by heating unit using the waste heat of electrolytic cell in high-temperature molten salt electrolysis process, realizes the efficient use of electrolytic cell waste heat.

Description

Technical Field

[0001] This utility model relates to the field of molten salt electrolysis for metal preparation technology, specifically to a hydrated molten salt feeding device and a system for electrolytic preparation of rare earth metals. Background Technology

[0002] Traditionally, the feeding method for preparing metals or alloys via molten salt electrolysis involves adding anhydrous chloride salts, such as lanthanum chloride or magnesium chloride, to the chloride salt electrolytic cell. The metals or alloys are then prepared by electrolyzing the molten chloride salt. Therefore, it is first necessary to prepare anhydrous salts using chloride salts containing water of crystallization, such as anhydrous magnesium chloride from magnesium chloride hexahydrate or anhydrous lanthanum chloride from lanthanum chloride heptahydrate. The dehydration of water of crystallization during the preparation of anhydrous chloride salts requires stringent conditions under a hydrogen chloride atmosphere, thus increasing the cost of the electrolytic raw materials. To overcome these limitations, a feeding method using hydrated molten salts has been developed for the electrolysis process.

[0003] In certain molten salt electrolysis processes, such as when hydrated molten salt is added dropwise to high-temperature molten salt as a raw material, there are fewer side reactions and fewer impurities entering the high-temperature molten salt during the volatilization of aqueous molten salt, allowing the electrolysis reaction to proceed smoothly. However, hydrated molten salt has high temperature and high viscosity, which presents problems such as high energy consumption for heating and melting hydrated salt, difficulty in uniform mixing when multiple hydrated molten salts are added together, and difficulty in controlling the dropwise addition process. Utility Model Content

[0004] The main purpose of this invention is to provide a hydrated molten salt feeding device and an electrolytic rare earth metal preparation system, thereby overcoming the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this utility model includes:

[0006] The first aspect of this utility model provides a hydrated molten salt feeding device for replenishing hydrated molten salt into an electrolysis device, comprising:

[0007] A melting unit, the melting unit including a melting chamber for containing hydrated salts;

[0008] The heating unit includes a waste heat collection mechanism, a heat conduction heating mechanism, a circulation pipeline, a heat-conducting fluid medium, and a circulation pump. The waste heat collection mechanism and the heat conduction heating mechanism are connected through the circulation pipeline to form a closed loop. The heat-conducting fluid medium fills the closed loop and is thermally connected to the waste heat collection mechanism and the heat conduction heating mechanism. The circulation pump is connected to the circulation pipeline and is used to drive the heat-conducting fluid medium to circulate in the closed loop. The waste heat collection mechanism is thermally connected to the electrolysis device and is used to collect the waste heat generated during the operation of the electrolysis device and to conduct the collected waste heat to the heat-conducting fluid medium inside itself. The heat conduction heating mechanism is thermally connected to the melting chamber and conducts the heat of the heat-conducting fluid medium inside itself to the melting chamber to heat the hydrated salt in the melting chamber to form molten hydrated salt.

[0009] A feeding unit is connected to the melting chamber and is used to transport the hydrated molten salt in the melting chamber to the electrolysis device.

[0010] A second aspect of this utility model provides a system for electrolytically preparing rare earth metals, comprising the aforementioned hydrated molten salt feeding device and an electrolysis device, wherein the electrolysis device is used to electrolyze the hydrated salt, and the hydrated molten salt feeding device is thermally connected to the electrolysis device and is used to replenish the hydrated molten salt into the electrolysis device.

[0011] Compared with the prior art, the advantages of this utility model include:

[0012] 1) The hydrated molten salt feeding device provided by this utility model uses the waste heat of the electrolytic cell during the high-temperature molten salt electrolysis process to heat the hydrated molten salt through the heating unit, thereby achieving efficient utilization of the waste heat of the electrolytic cell and saving energy.

[0013] 2) The hydrated molten salt feeding device provided by this utility model adjusts the size and speed of the hydrated molten salt droplets through the feeding unit, so that the hydrated molten salt can be added evenly to the electrolytic cell, which is beneficial to the stable operation of the high-temperature electrolytic cell. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of a hydrated molten salt feeding device provided in a typical embodiment of this utility model.

[0016] Reference numerals: 1. Nozzle; 2. Hydrated molten salt conveying pipeline; 3. Gear pump; 4. Melting tank; 5. Heat transfer oil; 6. Hydrated molten salt; 7. Cleaning water inlet pipe; 8. Stirring paddle; 9. Heat transfer oil circulation pump; 10. Heat transfer oil circulation pipeline; 11. Waste heat collection device; 12. Filter screen. Detailed Implementation

[0017] In view of the shortcomings of the prior art, the applicant, through long-term research and extensive practice, has come up with the technical solution of this utility model. The following will further explain the technical solution, its implementation process, and its principles.

[0018] This utility model embodiment provides a hydrated molten salt feeding device for replenishing hydrated molten salt into an electrolysis device, comprising:

[0019] A melting unit, the melting unit including a melting chamber for containing hydrated salts;

[0020] The heating unit includes a waste heat collection mechanism, a heat conduction heating mechanism, a circulation pipeline, a heat-conducting fluid medium, and a circulation pump. The waste heat collection mechanism and the heat conduction heating mechanism are connected through the circulation pipeline to form a closed loop. The heat-conducting fluid medium fills the closed loop and is thermally connected to the waste heat collection mechanism and the heat conduction heating mechanism. The circulation pump is connected to the circulation pipeline and is used to drive the heat-conducting fluid medium to circulate in the closed loop. The waste heat collection mechanism is thermally connected to the electrolysis device and is used to collect the waste heat generated during the operation of the electrolysis device and to conduct the collected waste heat to the heat-conducting fluid medium inside itself. The heat conduction heating mechanism is thermally connected to the melting chamber and conducts the heat of the heat-conducting fluid medium inside itself to the melting chamber to heat the hydrated salt in the melting chamber to form molten hydrated salt.

[0021] A feeding unit is connected to the melting chamber and is used to transport the hydrated molten salt in the melting chamber to the electrolysis device.

[0022] In some embodiments, the heat conduction heating mechanism is disposed around the periphery of the melting chamber.

[0023] In some preferred embodiments, the heat conduction heating mechanism includes a heat-conducting chamber that is thermally connected to the melting chamber and communicates with the circulation pipeline.

[0024] In some embodiments, the waste heat collection mechanism includes a waste heat collection chamber that is thermally connected to the electrolysis device and communicates with the circulation pipeline.

[0025] In some embodiments, the hydrated molten salt feeding device further includes a stirring unit for stirring the hydrated salt in the molten chamber.

[0026] In some preferred embodiments, the stirring unit includes a drive mechanism and a stirring paddle, the stirring paddle being disposed in the melting chamber, the stirring paddle being kinetically connected to the drive mechanism and capable of rotating about its own axis under the drive of the drive mechanism.

[0027] In some embodiments, the feeding unit includes a feeding pipeline, a feeding pump, and a discharge nozzle. One end of the feeding pipeline is connected to the melting chamber, and the other end is connected to the discharge nozzle. The feeding pump is connected to the feeding pipeline and is used to discharge the hydrated molten salt from the discharge nozzle.

[0028] In some preferred embodiments, the discharge nozzle is provided with a liquid outlet hole, and the effective liquid outlet area of ​​the liquid outlet hole can vary.

[0029] In this invention, the discharge nozzle can utilize existing technology to adjust the effective liquid discharge area. Specifically, the discharge nozzle includes a nozzle body with uniformly distributed liquid discharge holes on its surface. An adjusting plate is located inside the nozzle body, and the adjusting plate has adjusting holes corresponding to the liquid discharge holes. The surface of the adjusting plate with the adjusting holes is in contact with the surface of the nozzle body with the liquid discharge holes. The adjusting plate can rotate relative to the nozzle body, and during rotation, the positions of the adjusting holes and the liquid discharge holes are misaligned, causing the adjusting plate to block the liquid discharge holes, thereby changing the effective liquid discharge area. Of course, other methods known in the art can also be used to adjust the size of the effective liquid discharge area.

[0030] In some preferred embodiments, the feed pump includes, but is not limited to, a gear pump.

[0031] In some embodiments, the hydrated molten salt feeding device further includes a filtration unit for filtering impurities in the hydrated molten salt output from the melting chamber.

[0032] In some preferred embodiments, the filtration unit is disposed in the feed line between the feed pump and the melting chamber.

[0033] Furthermore, the filtering unit includes a filter screen.

[0034] In some implementations, the thermally conductive fluid medium includes, but is not limited to, thermally conductive oil.

[0035] This utility model embodiment also provides a system for electrolytic preparation of rare earth metals, which includes the aforementioned hydrated molten salt feeding device and an electrolysis device. The electrolysis device is used to electrolyze the hydrated salt, and the hydrated molten salt feeding device is thermally connected to the electrolysis device and is used to replenish the hydrated molten salt in the electrolysis device.

[0036] In some embodiments, the electrolysis device includes an electrolytic cell for holding hydrated salts, and the waste heat collection mechanism is thermally connected to the electrolytic cell.

[0037] In summary, the hydrated molten salt feeding device provided by this utility model utilizes the waste heat of the electrolytic cell for melting of hydrated salt through the circulation of heat transfer oil, realizing the utilization of waste heat from the high-temperature electrolytic cell and saving more energy. The stirring unit can make various hydrated molten salts evenly mixed, which is more conducive to the dripping and dehydration of hydrated molten salt. The gear pump can precisely control the feeding speed, realizing the uniformity and continuity of the mixed material transportation and the convenience of feeding.

[0038] The following will provide a further explanation of the technical solution, its implementation process, and its principles, in conjunction with the accompanying drawings and specific implementation examples.

[0039] Example 1

[0040] like Figure 1 As shown, a hydrated molten salt feeding device includes a melting unit, a heating unit, and a conveying unit. The melting unit includes a melting tank 4 for holding hydrated salt. The conveying unit is connected to the melting tank 4 and is used to convey the hydrated molten salt 6 in the melting tank 4 to an electrolytic cell. The heating unit includes a waste heat collection device 11, a heat conduction heating mechanism, a heat transfer oil circulation pipeline 10, heat transfer oil 5, and a heat transfer oil circulation pump 9.

[0041] The waste heat collection device 11 and the heat conduction heating mechanism are connected via the heat transfer oil circulation pipeline 10, forming a closed loop. The heat transfer oil 5 fills the closed loop and is thermally connected to the waste heat collection device 11 and the heat conduction heating mechanism. The heat transfer oil circulation pump 9 is connected to the heat transfer oil circulation pipeline 10 and is used to drive the heat transfer oil 5 to circulate in the closed loop. The waste heat collection device 11 is thermally connected to the electrolytic cell, and the heat conduction heating mechanism is thermally connected to the melting tank 4.

[0042] In this embodiment, the waste heat collection device is thermally connected to the electrolytic cell. This device collects a large amount of waste heat generated during the operation of the electrolytic cell. After collection, this waste heat heats the heat transfer oil in the closed loop. Through the circulation of the heat transfer oil, this waste heat is transferred to the heat conduction heating mechanism. Since the heat conduction heating mechanism is thermally connected to the melting tank, the heat transfer oil, during circulation, can transfer heat from the high-temperature electrolytic cell to the melting tank, thus heating the hydrated molten salt. Because the heat transfer oil has excellent thermal conductivity and low viscosity, it can quickly and uniformly conduct heat to the entire melting tank, thereby providing a stable heat source for the melting of the hydrated salt.

[0043] For example, the heat transfer oil 5 can be selected as low-viscosity machine oil, silicone oil, etc.

[0044] In this embodiment, the waste heat collection device 11 includes a waste heat collection chamber, which is located around the electrolytic cell. The waste heat collection chamber is thermally connected to the electrolytic cell and is connected to the heat transfer oil circulation pipeline 10. The waste heat collection chamber and the electrolytic cell are connected by heat through the cell wall. The waste heat collection chamber is used to collect the waste heat generated during the operation of the electrolytic cell and to conduct the collected waste heat to the heat transfer oil 5 inside itself.

[0045] In this embodiment, the heat conduction heating mechanism is disposed on the periphery of the melting tank 4. The heat conduction heating mechanism includes a heat conduction heating chamber, which is thermally connected to the melting tank 4 and connected to the heat transfer oil circulation pipeline 10. The heat conduction heating chamber and the melting tank 4 conduct heat through the tank wall of the melting tank, thereby conducting the heat of the heat transfer oil 5 inside itself to the melting tank 4, so as to heat the hydrated salt in the melting tank 4 to form molten hydrated salt 6.

[0046] In this embodiment, the heat conduction heating chamber can be independently set around the molten pool 4 or integrally set with the molten pool 4. When independently set, the heat conduction heating chamber surrounds the pool wall of the molten pool 4, and heat conduction between the heat conduction heating chamber and the molten pool 4 is achieved through the pool wall. When integrally set with the molten pool 4, the pool wall of the molten pool 4 is configured as an inner wall and an outer wall, and the inner and outer walls are sealed to form the heat conduction heating chamber. Heat conduction between the heat conduction heating chamber and the molten pool 4 is achieved through the inner wall.

[0047] In this embodiment, the hydrated molten salt feeding device further includes a stirring unit for stirring the hydrated salt in the melting tank 4. The stirring unit includes a drive mechanism and a stirring paddle 8. The stirring paddle 8 is disposed in the melting tank 4 and is connected to the drive mechanism for transmission and can rotate around its own axis under the drive of the drive mechanism.

[0048] In this embodiment, the material conveying unit includes a hydrated molten salt conveying pipeline 2, a gear pump 3, and a nozzle 1. One end of the hydrated molten salt conveying pipeline 2 is connected to the melting tank 4, and the other end is connected to the nozzle 1. The gear pump 3 is connected to the hydrated molten salt conveying pipeline 2 and is used to allow the hydrated molten salt 6 to be discharged from the nozzle 1.

[0049] In this embodiment, the hydrated molten salt conveying pipeline 2 is provided with an insulation layer and the inner lining material is polytetrafluoroethylene (PTFE). The inner lining material of the gear pump 3 is also PTFE.

[0050] In this embodiment, the nozzle 1 has uniformly distributed liquid outlet holes on its surface, and the effective liquid outlet area of ​​the liquid outlet holes can change. An adjustment plate is provided inside the nozzle 1. The adjustment plate has adjustment holes corresponding to the liquid outlet holes. The surface of the adjustment plate with adjustment holes is in contact with the surface of the nozzle with liquid outlet holes. The adjustment plate can rotate relative to the nozzle body, and when rotating, the positions of the adjustment holes and the liquid outlet holes are misaligned, so that the adjustment plate blocks the liquid outlet holes, thereby changing the effective liquid outlet area of ​​the liquid outlet holes.

[0051] In this embodiment, a filter screen 12 is installed inside the hydrated molten salt conveying pipeline 2 between the gear pump 3 and the melting tank 4 to filter impurities in the hydrated molten salt 6 output from the melting tank 4.

[0052] In this embodiment, the melting tank 4 is provided with a cleaning water inlet pipe 7 for rinsing the melting tank 4.

[0053] The hydrated molten salt feeding device provided in this embodiment can be used in rare earth metal electrolysis. Its working principle is based on the efficient utilization of waste heat from the electrolytic cell and the design of precise delivery and control of hydrated molten salt, specifically including the following working mechanism:

[0054] Waste Heat Collection and Conduction: First, the waste heat collection device installed on the rare earth molten salt electrolysis cell begins operation, collecting the large amount of waste heat generated during the cell's operation. This collected waste heat is then transferred to the hydrated salt melting tank via circulating heat transfer oil. This tank employs a jacketed structure, filled with low-viscosity heat transfer oil. During circulation, the heat transfer oil transfers heat from the high-temperature electrolysis cell to the heating tank containing the hydrated molten salt, raising its temperature. Due to the excellent thermal conductivity and low viscosity of the heat transfer oil, it can quickly and evenly conduct heat throughout the entire tank, thus providing a stable heat source for the melting of the hydrated salt.

[0055] Hydrated Salt Melting and Mixing: The hydrated salt in the heating tank gradually melts as the temperature rises. To ensure uniform mixing of the molten hydrated salt, a stirring paddle is installed in the tank. Driven by a motor, the paddle rotates at a specific speed. Through the stirring action of the paddle, different types of hydrated molten salts, as well as those at different melting stages, are thoroughly mixed to form a homogeneous hydrated molten salt system. This uniform mixing process not only facilitates subsequent transport but also ensures the compositional stability of the hydrated molten salt during dropwise addition, providing favorable raw material conditions for the subsequent electrolytic reaction.

[0056] Molten Salt Conveying and Filtration: The uniformly mixed hydrated molten salt begins to be conveyed under the action of a gear pump. The gear pump, through its precise internal gear structure, generates stable pressure to extract the hydrated molten salt from the tank. During extraction, the hydrated molten salt passes through a filter screen. The filter screen's function is to intercept any impurities, such as incompletely melted salt lumps or metal fragments that may be present inside the equipment, ensuring the purity of the hydrated molten salt entering the subsequent conveying pipeline and preventing impurities from adversely affecting subsequent nozzles and the electrolytic reaction.

[0057] Molten Salt Droplet Addition and Control: After filtration, the hydrated molten salt is transported through a molten salt delivery pipe to a nozzle with an adjustable orifice (i.e., the effective liquid discharge area of ​​the nozzle is adjustable). The nozzle orifice diameter can be adjusted according to actual production needs, and the gear pump speed can also be precisely controlled. When the hydrated molten salt reaches the nozzle, it is ejected in the form of droplets under the pressure of the gear pump. The size of the droplets is determined by both the nozzle orifice diameter and the gear pump speed. A smaller nozzle orifice diameter and a lower gear pump speed will produce smaller droplets, while a larger nozzle orifice diameter and a higher gear pump speed will produce larger droplets. By precisely adjusting these two parameters, precise control of the hydrated molten salt droplet size can be achieved, thereby ensuring that the hydrated molten salt material is uniformly added to the electrolytic cell, maintaining the stable operation of the high-temperature electrolytic cell, and providing reliable feeding support for the production of rare earth metals or alloys.

[0058] In summary, the hydrated molten salt feeding device provided by this utility model mainly includes a hollow tank (a melting tank with inner and outer walls) for melting hydrated salt. The hollow structure (the interlayer space between the inner and outer walls) is filled with low-viscosity heat-conducting oil. The external circulation system of the heat-conducting oil includes a waste heat collection device installed on the rare earth molten salt electrolysis cell, which uses the waste heat from the electrolysis cell for melting hydrated salt through the circulation of the heat-conducting oil. The molten hydrated salt is uniformly mixed under the action of a stirring paddle. Under the action of a gear pump, the hydrated molten salt is discharged from the melting tank through a filter screen. Finally, the hydrated molten salt is sprayed out through a nozzle with an adjustable orifice, becoming hydrated molten salt droplets. The size of the droplets is controlled by both the nozzle orifice diameter and the gear pump speed. The rare earth hydrated molten salt feeding device provided by this utility model has a simple structure, is energy-saving, and can be used in the production of rare earth metals or alloys.

[0059] Application Example 1

[0060] In the rare earth metal electrolysis process for preparing metallic lanthanum, hydrated molten salt material is added to the electrolytic cell using the hydrated molten salt feeding device of Example 1: Lanthanum chloride heptahydrate is loaded into the molten tank. A waste heat collection device installed on the rare earth molten salt electrolytic cell uses the waste heat from the electrolytic cell through oil circulation to melt the lanthanum chloride heptahydrate. The melting temperature is controlled between 100 and 110°C. The molten hydrated salt is uniformly mixed under the action of a stirring paddle. Under the action of a gear pump, the hydrated molten salt is discharged from the molten tank through a filter screen. Finally, the hydrated molten salt is sprayed out through a nozzle with an adjustable aperture, forming hydrated molten salt droplets. The droplet size is controlled between 5 and 10 minutes, and the dripping rate is determined according to the actual electrolysis temperature and efficiency of the electrolytic cell. After feeding, clean water is introduced to clean the heating tank and pipelines to prevent corrosion and clogging of the pipelines by solidification of the hydrated molten salt.

[0061] Application Example 2

[0062] In the rare earth metal electrolysis process for preparing lanthanum / magnesium alloy, the hydrated molten salt feeding device of Example 1 is used to add hydrated molten salt material to the electrolytic cell: hydrated salts lanthanum chloride heptahydrate and magnesium chloride hexahydrate are loaded into the molten tank. The waste heat collection device on the rare earth molten salt electrolytic cell uses the waste heat of the electrolytic cell through the circulation of silicone oil for the melting of lanthanum chloride heptahydrate / magnesium chloride hexahydrate, and the melting temperature is controlled between 120 and 140°C; the molten hydrated salt is mixed evenly under the action of the stirring paddle; the hydrated molten salt is discharged from the molten tank through the filter screen under the action of the gear pump, and finally sprayed out through the nozzle with adjustable aperture to become hydrated molten salt droplets. The droplet size is controlled between 3 and 5 mm, and the dripping rate is determined according to the actual electrolysis temperature and efficiency of the electrolytic cell.

[0063] Application Example 3

[0064] In the rare earth metal electrolysis process for preparing lanthanum / strontium alloy, the hydrated molten salt material is added to the electrolytic cell using the hydrated molten salt feeding device of Example 1: hydrated salts lanthanum chloride heptahydrate and strontium chloride hexahydrate are loaded into the molten cell. The waste heat collection device on the rare earth molten salt electrolytic cell uses the circulating silicone oil to melt the mixed molten salt of lanthanum chloride heptahydrate and strontium chloride hexahydrate, with the melting temperature controlled between 120 and 140°C. The molten hydrated salt is mixed evenly under the action of the stirring paddle. Under the action of the gear pump, the hydrated molten salt is discharged from the molten cell through the filter screen and finally sprayed out through a nozzle with an adjustable aperture, becoming hydrated molten salt droplets. The droplet size is controlled between 4 and 10 mm, and the dripping rate is determined according to the actual electrolysis temperature and efficiency of the electrolytic cell.

[0065] Although the present invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions may be made without departing from the spirit and scope of the present invention, and that elements of the described embodiments may be substituted with substantially equivalents. Furthermore, many modifications may be made without departing from the scope of the present invention to adapt particular situations or materials to the teachings of the present invention. Therefore, the present invention is not intended to be limited to the specific embodiments disclosed for carrying out the present invention, but rather is intended to include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

[0066] It should be understood that the above embodiments are merely illustrative of the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A hydrated molten salt feeding device for replenishing hydrated molten salt into an electrolysis device, characterized in that, include: A melting unit, the melting unit including a melting chamber for containing hydrated salts; The heating unit includes a waste heat collection mechanism, a heat conduction heating mechanism, a circulation pipeline, a heat-conducting fluid medium, and a circulation pump. The waste heat collection mechanism and the heat conduction heating mechanism are connected through the circulation pipeline to form a closed loop. The heat-conducting fluid medium fills the closed loop and is thermally connected to the waste heat collection mechanism and the heat conduction heating mechanism. The circulation pump is connected to the circulation pipeline and is used to drive the heat-conducting fluid medium to circulate in the closed loop. The waste heat collection mechanism is thermally connected to the electrolysis device and is used to collect the waste heat generated during the operation of the electrolysis device and to conduct the collected waste heat to the heat-conducting fluid medium inside itself. The heat conduction heating mechanism is thermally connected to the melting chamber and conducts the heat of the heat-conducting fluid medium inside itself to the melting chamber to heat the hydrated salt in the melting chamber to form molten hydrated salt. A feeding unit is connected to the melting chamber and is used to transport the hydrated molten salt in the melting chamber to the electrolysis device.

2. The hydrated molten salt feeding device according to claim 1, characterized in that, The heat conduction heating mechanism is located around the periphery of the melting chamber.

3. The hydrated molten salt feeding device according to claim 2, characterized in that, The heat conduction heating mechanism includes a heat conduction chamber, which is thermally connected to the melting chamber and communicates with the circulation pipeline.

4. The hydrated molten salt feeding device according to claim 1, characterized in that, The waste heat collection mechanism includes a waste heat collection chamber, which is thermally connected to the electrolysis device and communicates with the circulation pipeline.

5. The hydrated molten salt feeding device according to claim 1, characterized in that, It also includes a stirring unit for stirring the hydrated salt in the molten chamber.

6. The hydrated molten salt feeding device according to claim 5, characterized in that, The stirring unit includes a drive mechanism and a stirring paddle. The stirring paddle is disposed in the melting chamber and is connected to the drive mechanism for transmission and can rotate around its own axis under the drive mechanism.

7. The hydrated molten salt feeding device according to claim 1, characterized in that, The material conveying unit includes a material conveying pipeline, a material conveying pump, and a discharge nozzle. One end of the material conveying pipeline is connected to the melting chamber, and the other end is connected to the discharge nozzle. The material conveying pump is connected to the material conveying pipeline and is used to discharge the hydrated molten salt from the discharge nozzle.

8. The hydrated molten salt feeding device according to claim 7, characterized in that, The discharge nozzle is provided with a liquid outlet hole, and the effective liquid outlet area of ​​the liquid outlet hole can vary.

9. The hydrated molten salt feeding device according to claim 7, characterized in that, The feed pump includes a gear pump.

10. The hydrated molten salt feeding device according to claim 1, characterized in that, It also includes a filtration unit for filtering impurities in the hydrated molten salt output from the melting chamber.

11. The hydrated molten salt feeding device according to claim 10, characterized in that, The filtration unit is installed in the feed pipeline between the feed pump and the melting chamber.

12. The hydrated molten salt feeding device according to claim 11, characterized in that, The filtration unit includes a filter screen.

13. The hydrated molten salt feeding device according to claim 1, characterized in that, The heat-conducting fluid medium includes heat-conducting oil.

14. A system for electrolytically preparing rare earth metals, characterized in that, The invention includes a hydrated molten salt feeding device according to any one of claims 1-13, and an electrolysis device, the electrolysis device being used to electrolyze hydrated salt, the hydrated molten salt feeding device being thermally connected to the electrolysis device and being used to replenish hydrated molten salt into the electrolysis device.

15. The system for electrolytic preparation of rare earth metals according to claim 14, characterized in that, The electrolysis device includes an electrolytic cell for holding hydrated salts, and the waste heat collection mechanism is thermally connected to the electrolytic cell.

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