Preparation device and method of high-purity lithium fluoride

Abstract

The application discloses a kind of preparation device and method of high-purity lithium fluoride, including reaction kettle, solid feeding pipe is provided on reaction kettle, liquid feeding pipe, discharge pipe, condensation reflux pipe, reflux port, condensation reflux pipe is provided with shell-and-tube counterflow heat exchange device, condensation reflux pipe is connected with tail gas collection pipe, tail gas collection pipe is connected with tail gas washing device;Reaction kettle is provided with inner rotating shaft and outer rotating drum, the bottom of inner rotating shaft is connected with isolator, and the bottom of outer rotating drum is also fixed with spiral stirring blade;The bottom of reaction kettle is also provided with grinding mechanism.The preparation method includes steps such as S1-S5.The lithium fluoride wrapped on the surface of lithium carbonate crystal and generated can be crushed and ground, so that the wrapped lithium carbonate that is not completely reacted can be reacted again, the lithium carbonate is fully reacted, other element impurities are not introduced in the preparation process, so that the preparation purity of lithium fluoride is higher.

Description

Technical Field

[0001] This invention relates to the field of lithium fluoride preparation, and more particularly to an apparatus and method for preparing high-purity lithium fluoride. Background Technology

[0002] Lithium fluoride is an inorganic reagent, appearing as a white powder or cubic crystals. As an important lithium-based material, lithium fluoride is widely used in enamel, glass, ceramics, optical fibers, lithium batteries, and other fields. Currently, the main methods for preparing high-purity lithium fluoride include direct preparation, ion exchange preparation, and extraction preparation.

[0003] The direct synthesis method directly reacts lithium carbonate and hydrofluoric acid to obtain lithium fluoride. While this method is simple in principle and introduces no other impurities, the reaction produces insoluble lithium fluoride solids. These lithium fluoride crystals coat the surface of the lithium carbonate crystals, preventing further reaction and resulting in incomplete reaction and significantly reduced purity of the produced lithium fluoride. Ensuring complete reaction of the lithium carbonate crystals and improving the purity of the lithium fluoride remains a major challenge in lithium fluoride preparation. Therefore, it is necessary to propose an apparatus and method for preparing high-purity lithium fluoride with a more thorough reaction of the lithium carbonate crystals and higher purity. Summary of the Invention

[0004] To address the problems of insufficient reaction of lithium carbonate crystals and low purity of lithium fluoride in existing technologies, this invention provides an apparatus and method for preparing high-purity lithium fluoride.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A device for preparing high-purity lithium fluoride is provided, including a reactor. The reactor is equipped with a solid feed pipe, a liquid feed pipe, a discharge pipe, a condenser reflux pipe, and a reflux port. A shell-and-tube countercurrent heat exchanger is installed on the condenser reflux pipe. The condenser reflux pipe is connected to a tail gas collection pipe, which is connected to a tail gas scrubbing device. The reactor is equipped with an inner rotating shaft and an outer rotating cylinder. The inner rotating shaft is installed inside the outer rotating cylinder, and an isolation cover is connected to the bottom of the inner rotating shaft. A spiral stirring blade is also fixed to the bottom of the outer rotating cylinder. The device also includes an inner rotating shaft lifting drive mechanism for driving the inner rotating shaft and an outer rotating cylinder drive structure for driving the outer rotating cylinder. A grinding mechanism is also provided at the bottom of the reactor.

[0006] Furthermore, a rotary stirring mechanism is provided on the outer rotating cylinder, and the outlet side of the solid feed pipe and the liquid feed pipe is located above the rotary stirring mechanism. The rotary stirring mechanism includes a rotating sleeve, several turbine stirring blades, and a stirring cover. The rotating sleeve is fixed outside the outer rotating cylinder, and several turbine stirring blades are fixed between the rotating sleeve and the stirring cover. There are two rotary stirring mechanisms, and the stirring covers of the two rotary stirring mechanisms are designed as an integral unit. The turbine stirring blades of the two rotary stirring mechanisms are set at a certain angle.

[0007] Furthermore, the grinding mechanism includes an adjusting cylinder fixed to the bottom of the reactor, a grinding shaft fixed inside the adjusting cylinder, a grinding roller fixed to the upper end of the grinding shaft, a grinding ring that mates with the grinding roller on the inner wall of the reactor, an adjusting sleeve threaded onto the adjusting cylinder, forming a cylindrical receiving space between the adjusting sleeve and the adjusting cylinder, an mounting protrusion ring on the grinding shaft located within the cylindrical receiving space, several limiting screws on the adjusting sleeve limiting the mounting protrusion ring, thrust bearings at the upper and lower ends of the mounting protrusion ring, a transmission cylinder at the bottom of the grinding shaft, a grinding motor connected to the bottom of the transmission cylinder, both the output end of the grinding motor and the bottom of the grinding shaft being polygonal prism portions, a polygonal prism through hole on the transmission cylinder mates with the polygonal prism portion; a spring is also provided between the grinding shaft and the output end of the grinding motor, the spring being located within the polygonal prism through hole.

[0008] Furthermore, the outer rotating drum drive structure includes a driven gear and a drive motor mounted on the top of the outer rotating drum. The output end of the drive motor is provided with a drive gear, which meshes with the driven gear.

[0009] Furthermore, the inner rotating shaft lifting drive mechanism includes a dual-head motor connected to the inner rotating shaft and a mounting shell for mounting the dual-head motor. A lifting sleeve is provided on the other end of the dual-head motor, and two lifting brackets are fixed on the lifting sleeve. The lifting brackets are connected to the mounting shell through a telescopic rod. A motor guide cylinder for mounting the dual-head motor is provided on the mounting shell, and the dual-head motor moves up and down inside the motor guide cylinder.

[0010] Furthermore, the discharge pipe and the return port are connected by a return pipe, which is also equipped with a return switch valve and a return pump.

[0011] Furthermore, the telescopic pole can be an electric telescopic pole, a hydraulic pole, or a pneumatic pole.

[0012] Furthermore, the bottom of the reactor is provided with a frustum portion that mates with the isolation hood and a cylindrical portion that mates with the grinding mechanism. The reactor is provided with an inclined surface, and the discharge pipe is located at the lowest point of the inclined surface. The bottom of the reactor is also provided with a frame.

[0013] Furthermore, the reactor is made of stainless steel, and the inner wall of the reactor is lined with a polytetrafluoroethylene layer.

[0014] A method for preparing high-purity lithium fluoride, using the aforementioned apparatus, includes the following steps: S1: Before the reaction, the hydrofluoric acid isolation hood is lowered to the lowest position. The hydrofluoric acid isolation hood divides the interior of the hydrofluoric acid reactor into an upper pre-stirring reaction zone and a lower grinding zone; the hydrofluoric acid rotary stirring mechanism and the hydrofluoric acid spiral stirring blade rotate. S2: Determine the reaction ratio of lithium carbonate and hydrofluoric acid. Solid lithium carbonate particles and liquid hydrofluoric acid are fed into the reactor through solid feed pipe and liquid feed pipe, respectively. Under the rotation of the rotary stirring mechanism and the spiral stirring blade, lithium carbonate and hydrofluoric acid react to generate a lithium fluoride-hydrofluoric acid-lithium carbonate mixed slurry and hydrofluoric acid and carbon dioxide gas. S3: After lithium carbonate and hydrofluoric acid react for a period of time, the grinding mechanism is started and the hydrofluoric acid in the isolation hood is raised to the highest position, so that the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry is transported to the grinding mechanism through the gap channel between the hydrofluoric acid in the isolation hood and the hydrofluoric acid in the reaction vessel for grinding. The grinding mechanism crushes and grinds the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry. S4: After the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry has entered the grinding mechanism, the hydrofluoric acid isolation cover is lowered to the lowest point again, dividing the interior of the hydrofluoric acid reactor into an upper pre-stirring reaction zone and a lower grinding zone, ensuring that the reaction in the hydrofluoric acid reactor proceeds. The ground reactants are returned to the upper pre-stirring reaction zone in the hydrofluoric acid reactor through the hydrofluoric acid discharge pipe, hydrofluoric acid return pipe, hydrofluoric acid return switch valve, and hydrofluoric acid return pump for further reaction. S5: Repeat steps S1-S4 multiple times until lithium carbonate has completely reacted to form lithium fluoride.

[0015] The beneficial effects of this invention are as follows: The reactor of this invention is equipped with a rotary stirring mechanism, a spiral stirring blade, a partition cover, and a grinding mechanism. The rotary stirring mechanism can break up the added solid lithium carbonate particles to a certain extent, and at the same time provide a reaction stirring channel for the solid lithium carbonate particles and hydrofluoric acid, ensuring the reaction efficiency of solid lithium carbonate particles and hydrofluoric acid. The spiral stirring blade, in conjunction with the rotary stirring blade, further ensures the reaction efficiency of solid lithium carbonate particles and hydrofluoric acid. When the partition cover is lowered to its lowest position, it covers the bottom of the reactor, separating the upper stirring area of ​​the reactor from the grinding mechanism, thereby allowing the solid lithium carbonate particles and hydrofluoric acid in the reactor to react fully. When the partition cover is raised to its highest position... At its highest point, the gap between the isolation hood and the reactor allows the lithium fluoride-hydrofluoric acid-lithium carbonate mixture to flow to the grinding mechanism. The grinding mechanism grinds the lithium fluoride-hydrofluoric acid-lithium carbonate mixture, breaking down unreacted solid lithium carbonate particles into smaller particles, allowing them to continue reacting with the hydrofluoric acid in the reactor. The particles are then returned to the reactor via a reflux pipe, ensuring complete reaction of the solid lithium carbonate particles. Through repeated grinding and reaction cycles, the added solid lithium carbonate particles are ultimately fully reacted. The grinding mechanism effectively solves the problem of lithium fluoride produced during the reaction coating the surface of lithium carbonate crystals, preventing the solid lithium carbonate particles from fully reacting.

[0016] When the isolation cover of this invention is lowered to its lowest position, it covers the bottom of the reactor, separating the upper stirring area of ​​the reactor from the grinding mechanism. This separation of the pre-stirring reaction area and the grinding area prevents the lithium fluoride-hydrofluoric acid-lithium carbonate mixture from entering the grinding area, ensuring the reaction between lithium carbonate and hydrofluoric acid proceeds. When the isolation cover is raised to its highest position, the communication gap between the isolation cover and the reactor allows the lithium fluoride-hydrofluoric acid-lithium carbonate mixture to flow to the grinding mechanism.

[0017] This invention can crush and grind lithium carbonate crystals and lithium fluoride coated on the surface of lithium carbonate after formation, so that the unreacted lithium carbonate can react again, allowing the lithium carbonate to react fully. Moreover, no other elemental impurities are introduced during the reaction process, resulting in higher purity of lithium fluoride.

[0018] This invention enables the premixing and stirring of lithium carbonate and hydrofluoric acid. The resulting lithium fluoride-hydrofluoric acid-lithium carbonate slurry is then ground by a grinding mechanism. The ground lithium fluoride-hydrofluoric acid-lithium carbonate slurry is then transported to the reaction vessel through a reflux pipeline to continue the reaction. Through multiple cycles of premixing and grinding, the lithium carbonate can react more completely, avoiding the formation of lithium fluoride coating on the surface of lithium carbonate, which could cause problems in the lithium carbonate reaction.

[0019] The grinding mechanism of the present invention can adjust the height of the grinding shaft by adjusting the adjusting sleeve, thereby adjusting the grinding gap between the grinding roller and the grinding ring, and adjusting the size of the grinding particles, so that the grinding of the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry can be better adjusted according to the number of grinding cycles.

[0020] The lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry of the present invention is output from the outlet at the bottom of the reactor and transported to the grinding device by the reflux pump through the reflux pipe for grinding. The lithium fluoride coated on the surface of the lithium carbonate solid particles is separated from the lithium carbonate solid particles, so that the lithium carbonate crystals in the slurry are exposed and react with hydrofluoric acid. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the rotary stirring mechanism; Figure 3 Schematic diagram of the grinding mechanism Figure 1 ; Figure 4 Schematic diagram of the grinding mechanism Figure 2 ; Figure 5 A schematic diagram of the rotary stirring mechanism and its drive unit. Figure 6This is a schematic diagram illustrating the operation of the present invention.

[0022] The symbols for the main components in the diagram are explained below: 1. Reactor; 11. Solid feed pipe; 12. Liquid feed pipe; 13. Discharge pipe; 14. Condensate reflux pipe; 15. Reflux port; 16. Screw conveyor; 17. Shell-and-tube countercurrent heat exchanger; 18. Tail gas scrubbing device; 19. Tail gas collection pipe; 2. Rotary stirring mechanism; 21. Outer rotating cylinder; 22. Rotating sleeve; 23. Turbine stirring blade; 24. Stirring cover; 25. Spiral stirring blade; 26. Driven gear; 27. Drive gear; 28. Drive motor; 3. Lifting partition mechanism; 31. Isolation cover; 32. Inner rotating shaft; 33. Dual-head motor; 34. Motor guide cylinder; 35. Mounting shell; 36. Lifting sleeve; 37. Limiting protrusion ring; 38. Lifting bracket; 39. Telescopic rod; 4. Grinding mechanism; 41. Grinding ring; 42. Grinding roller; 43. Grinding shaft; 431. Mounting convex ring; 44. Adjusting cylinder; 45. Adjusting sleeve; 46. Thrust bearing; 47. Limit screw; 48. Transmission cylinder; 49. Grinding motor; 40. Spring; 5. Frame; 6. Return pipe; 7. Return switch valve; 8. Return pump. Detailed Implementation

[0023] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0024] like Figure 1As shown, the apparatus for preparing high-purity lithium fluoride includes a reactor 1, preferably made of stainless steel. The inner wall of the reactor 1 is lined with a polytetrafluoroethylene (PTFE) layer, which effectively prevents corrosion from hydrofluoric acid and ensures the normal progress of the preparation reaction. The reactor 1 is equipped with a solid feed pipe 11, a liquid feed pipe 12, a discharge pipe 13, a condenser reflux pipe 14, and a reflux port 15. The solid feed pipe 11 is used for inputting lithium carbonate solid particles, the liquid feed pipe 12 is used for inputting hydrofluoric acid liquid, the discharge pipe 13 is used for outputting the reactants, and the condenser reflux pipe 14 and reflux port 15 are used for circulating the reaction. The condenser reflux pipe 14 is vertically installed at the top of the reactor 1. A screw conveyor 16 can also be connected to the solid feed pipe 11 to facilitate the input of lithium carbonate solid particles. A shell-and-tube countercurrent heat exchanger 17 is installed on the condenser reflux pipe 14. The condenser reflux pipe 14 is connected to a tail gas collection pipe 19, and the tail gas collection pipe 19 is connected to a tail gas scrubbing device 18. An inner rotating shaft 32 and an outer rotating cylinder 21 are installed on the reactor 1. The inner rotating shaft 32 is installed inside the outer rotating cylinder 21, and an isolation cover 31 is connected to the bottom of the inner rotating shaft 32. A spiral stirring blade 25 is also fixed to the bottom of the outer rotating cylinder 21. The discharge pipe 13 and the reflux port 15 are connected by a reflux pipe 6. A reflux switch valve 7 and a reflux pump 8 are also installed on the reflux pipe 6. The reflux pump 8 is preferably a corrosion-resistant pump.

[0025] The internal heat exchange tubes of the shell-and-tube countercurrent heat exchanger 17 are flexible tubes resistant to hydrofluoric acid corrosion. These internal heat exchange tubes are wound and fixed to the outside of the condenser reflux tube 14. An insulating shell is also installed outside the internal heat exchange tubes. The heat exchange medium for the internal heat exchange tubes is water or cooling oil. The condenser reflux tube 14 can be longer than 1 meter. The longer the condenser reflux tube 14, the better its buffering effect on the vigorous reaction between hydrofluoric acid and lithium carbonate. The shell-and-tube countercurrent heat exchanger 17 enables the condensation and reflux of hydrofluoric acid, reducing its loss and ensuring sufficient reaction between hydrofluoric acid and lithium carbonate within the reactor, thus minimizing hydrofluoric acid consumption. Under the action of the shell-and-tube countercurrent heat exchanger 17, hydrofluoric acid remains within the reactor and reacts fully with lithium carbonate, avoiding the difficulty in separating carbon dioxide and hydrofluoric acid in the tail gas during the lithium fluoride synthesis process, while maximizing the reaction of hydrofluoric acid.

[0026] like Figure 3 and 4As shown, a grinding mechanism 4 is also provided at the bottom of the reactor 1. The grinding mechanism 4 includes an adjusting cylinder 44 fixed to the bottom of the reactor 1, a grinding shaft 43 fixed inside the adjusting cylinder 44, a grinding roller 42 fixed at the upper end of the grinding shaft 43, a grinding ring 41 that mates with the grinding roller 42 on the inner wall of the reactor 1, an adjusting sleeve 45 threadedly connected to the adjusting cylinder 44, forming a cylindrical receiving space between the adjusting sleeve 45 and the adjusting cylinder 44, an mounting protrusion 431 on the grinding shaft 43 located within the cylindrical receiving space, and a limit mounting protrusion on the adjusting sleeve 45. Several limiting screws 47 are attached to the ring 431. Thrust bearings 46 are provided at the upper and lower ends of the mounting ring 431. A transmission cylinder 48 is provided at the bottom of the grinding shaft 43, and a grinding motor 49 is connected to the bottom of the transmission cylinder 48. The output end of the grinding motor 49 and the bottom of the grinding shaft 43 are both polygonal prisms. A polygonal prism through hole is provided on the transmission cylinder 48 to mate with the polygonal prism. A spring 40 is also provided between the grinding shaft 43 and the output end of the grinding motor 49, and the spring 40 is located in the polygonal prism through hole. The LiF generated by the reaction will coat the surface of the Li2CO3 crystal, hindering the further reaction between Li2CO3 and HF. The grinding mechanism 4 can crush and grind the coated Li2CO3 crystal and the generated LiF, so that the unreacted Li2CO3 crystal can be returned to the reaction vessel 1 through the reflux pipe 6 for reaction. By performing multiple reactions and grinding, the Li2CO3 crystal can be completely reacted, resulting in higher purity of the prepared LiF.

[0027] like Figure 2 As shown, a rotary stirring mechanism 2 is installed on the outer rotating cylinder 21. The outlet sides of the solid feed pipe 11 and the liquid feed pipe 12 are located above the rotary stirring mechanism 2. The rotary stirring mechanism 2 includes a rotating sleeve 22, several turbine stirring blades 23, and a stirring cover 24. The rotating sleeve 22 is fixed to the outside of the outer rotating cylinder 21, and the several turbine stirring blades 23 are fixed between the rotating sleeve 22 and the stirring cover 24. There are two rotary stirring mechanisms 2, and the stirring covers 24 of the two rotary stirring mechanisms 2 are designed as one piece. The turbine stirring blades 23 of the two rotary stirring mechanisms 2 are set at a certain angle. The turbine stirring blades 23 and the spiral stirring blades 25 can stir and mix the solid lithium carbonate particles and the hydrofluoric acid liquid, so that the solid lithium carbonate particles and the hydrofluoric acid liquid can react fully. At the same time, the several turbine stirring blades 23 can break the solid lithium carbonate particles to a certain extent, so that the lithium fluoride solid generated by the reaction will not completely cover the surface of the lithium carbonate crystal. The stirring cover 24 and the several turbine stirring blades 23 cooperate to form a reaction and breaking channel, which improves the reaction effect of the solid lithium carbonate particles.

[0028] like Figure 5As shown, the outer rotating drum 21 is driven by a drive structure including a driven gear 26 mounted on the top of the outer rotating drum 21 and a drive motor 28. A drive gear 27 is located at the output end of the drive motor 28, and the drive gear 27 meshes with the driven gear 26. The drive motor 28 drives the rotating stirring mechanism 2 and the spiral stirring blades 25 on the outer rotating drum 21 to rotate via the drive gear 27 and the driven gear 26. The stirring action of the rotating stirring mechanism 2 and the spiral stirring blades 25 effectively improves the reaction effect between solid lithium carbonate particles and hydrofluoric acid liquid.

[0029] It also includes an inner rotating shaft lifting drive mechanism that drives the inner rotating shaft 32. The inner rotating shaft lifting drive mechanism includes a dual-head motor 33 connected to the inner rotating shaft 32 and a mounting shell 35 for mounting the dual-head motor 33. A lifting sleeve 36 is provided on the other end of the dual-head motor 33. Two lifting brackets 38 are fixed on the lifting sleeve 36. The lifting brackets 38 are connected to the mounting shell 35 by a telescopic rod 39. A motor guide cylinder 34 is provided on the mounting shell 35 for mounting the dual-head motor 33. The dual-head motor 33 moves up and down inside the motor guide cylinder 34. The telescopic rod 39 is an electric telescopic rod, a hydraulic rod, or a pneumatic rod. The telescopic rod 39, via the lifting bracket 38 and lifting sleeve 36, drives the dual-head motor 33 to move up and down within the motor guide cylinder 34, thereby raising and lowering the isolation cover 31 via the inner rotating shaft 32. The isolation cover 31 is frustum-shaped. When the isolation cover 31 is raised to its lowest position, its bottom covers the bottom of the reactor 1, dividing the reactor 1 into upper and lower separated parts, thus separating the reaction of solid lithium carbonate particles and hydrofluoric acid liquid within the reactor 1 from the grinding mechanism 4. When the isolation cover 31 is at its lowest position, it covers the bottom of the reactor 1, and the solid lithium carbonate particles and hydrofluoric acid liquid react above the isolation cover 31. When the isolation cover 31 is at its highest position, the solid lithium carbonate particles, hydrofluoric acid liquid, and reaction products can flow through the gap 1 between the isolation cover 31 and the reactor 1 to the grinding mechanism 4 for crushing and grinding. The dual-head motor 33 can drive the isolation cover 31 to rotate, so that after the isolation cover 31 rises, the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry at the top of the isolation cover 31 can be thrown out, avoiding the residue and adhesion of the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry.

[0030] The bottom of the reactor 1 is provided with a frustum part that cooperates with the isolation cover 31 and a cylindrical part that cooperates with the grinding mechanism 4. The frustum part and the isolation cover 31 are covered and separated. The reactor 1 is provided with an inclined surface, and the discharge pipe 13 is located at the lowest point of the inclined surface. The bottom of the reactor 1 is also provided with a frame 5, and the reactor 1 is fixedly installed by the frame 5.

[0031] The method for preparing high-purity lithium fluoride, using the aforementioned high-purity lithium fluoride preparation apparatus, includes the following steps: S1: Before the reaction, the isolation cover 31 is lowered to the lowest position. The isolation cover 31 divides the interior of the reactor 1 into an upper pre-stirring reaction zone and a lower grinding zone to ensure the mixing reaction of lithium carbonate and hydrofluoric acid; the rotary stirring mechanism 2 and the spiral stirring blade 25 perform rotation operation. S2: Determine the reaction ratio of lithium carbonate and hydrofluoric acid. Solid lithium carbonate particles and liquid hydrofluoric acid are fed into reactor 1 through solid feed pipe 11 and liquid feed pipe 12, respectively. Under the rotation of rotary stirring mechanism 2 and spiral stirring blade 25, lithium carbonate and hydrofluoric acid react to generate lithium fluoride-hydrofluoric acid-lithium carbonate mixed slurry and hydrofluoric acid and carbon dioxide gas. The reaction principle of lithium carbonate and hydrofluoric acid is: Li2CO3 + 2HF = 2LiF↓ + CO2↑ + H2O. The HF-CO2 gas produced by the reaction enters the shell-and-tube countercurrent heat exchanger 17. The HF gas is condensed and then returned to the reactor 1 to continue participating in the reaction. The gas that cannot be condensed and returned is sent to the tail gas scrubbing device 18 for scrubbing before being discharged. S3: As Figure 6 As shown, after lithium carbonate and hydrofluoric acid react for a period of time, the grinding mechanism is started and the isolation cover 31 is raised to the highest position, so that the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry is transported to the grinding mechanism 4 through the gap channel between the isolation cover 31 and the reaction vessel 1 for grinding. The grinding mechanism 4 crushes and grinds the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry. S4: After the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry has entered the grinding mechanism, the isolation cover 31 is lowered to the lowest position again, dividing the interior of the reactor 1 into an upper pre-stirring reaction zone and a lower grinding zone, ensuring that the reaction in the reactor 1 proceeds. The ground reactants are returned to the upper pre-stirring reaction zone in the reactor 1 for reaction through the discharge pipe 13, reflux pipe 6, reflux switch valve 7 and reflux pump 8. S5: Repeat steps S1-S4 multiple times until lithium carbonate has completely reacted to form lithium fluoride.

Claims

1. An apparatus for preparing high-purity lithium fluoride, characterized in that, The reactor includes a reactor (1), which is equipped with a solid feed pipe (11), a liquid feed pipe (12), a discharge pipe (13), a condensation reflux pipe (14), and a reflux port (15). The condensation reflux pipe (14) is equipped with a shell-and-tube countercurrent heat exchanger (17). The condensation reflux pipe (14) is connected to a tail gas collection pipe (19), and the tail gas collection pipe (19) is connected to a tail gas scrubbing device (18). The reactor (1) is provided with an inner rotating shaft (32) and an outer rotating cylinder (21). The inner rotating shaft (32) is installed inside the outer rotating cylinder (21). The bottom of the inner rotating shaft (32) is connected to an isolation cover (31). The bottom of the outer rotating cylinder (21) is also fixed with a spiral stirring blade (25). It also includes an inner rotating shaft lifting drive mechanism for driving the inner rotating shaft (32) and an outer rotating cylinder drive structure for driving the outer rotating cylinder (21); a grinding mechanism (4) is also provided at the bottom of the reactor (1). A rotary stirring mechanism (2) is provided on the outer rotating cylinder (21). The outlet sides of the solid feed pipe (11) and the liquid feed pipe (12) are located above the rotary stirring mechanism (2). The rotary stirring mechanism (2) includes a rotating sleeve (22), several turbine stirring blades (23), and a stirring cover (24). The rotating sleeve (22) is fixed outside the outer rotating cylinder (21), and several turbine stirring blades (23) are fixed between the rotating sleeve (22) and the stirring cover (24). The rotary stirring mechanism (2) is provided in two places. The stirring covers (24) of the two rotary stirring mechanisms (2) are designed as a single unit, and the turbine stirring blades (23) of the two rotary stirring mechanisms (2) are staggered at a certain angle. The outer rotating drum drive structure includes a driven gear (26) and a drive motor (28) mounted on the top of the outer rotating drum (21). The output end of the drive motor (28) is provided with a drive gear (27), which meshes with the driven gear (26). The grinding mechanism (4) includes an adjusting cylinder (44) fixed to the bottom of the reactor (1), a grinding shaft (43) fixed inside the adjusting cylinder (44), a grinding roller (42) fixed at the upper end of the grinding shaft (43), a grinding ring (41) cooperating with the grinding roller (42) on the inner wall of the reactor (1), an adjusting sleeve (45) threadedly connected to the adjusting cylinder (44), a cylindrical receiving space formed between the adjusting sleeve (45) and the adjusting cylinder (44), an mounting protrusion (431) provided on the grinding shaft (43), the mounting protrusion (431) located in the cylindrical receiving space, and an adjusting sleeve (45) provided with... A plurality of limiting screws (47) are provided for the limiting mounting convex ring (431). The upper and lower ends of the mounting convex ring (431) are provided with thrust bearings (46). The bottom of the grinding shaft (43) is provided with a transmission cylinder (48). The bottom of the transmission cylinder (48) is connected to a grinding motor (49). The output end of the grinding motor (49) and the bottom of the grinding shaft (43) are both polygonal prisms. The transmission cylinder (48) is provided with a polygonal prism through hole that mates with the polygonal prism. A spring (40) is also provided between the grinding shaft (43) and the output end of the grinding motor (49). The spring (40) is located in the polygonal prism through hole. The grinding mechanism (4) adjusts the height of the grinding shaft (43) by adjusting the sleeve (45), thereby adjusting the grinding gap between the grinding roller (42) and the grinding ring (41), and thus adjusting the size of the grinding particles.

2. The apparatus for preparing high-purity lithium fluoride according to claim 1, characterized in that, The inner rotating shaft lifting drive mechanism includes a dual-head motor (33) connected to the inner rotating shaft (32) and a mounting shell (35) for mounting the dual-head motor (33). A lifting sleeve (36) is provided on the other end of the dual-head motor (33). Two lifting brackets (38) are fixed on the lifting sleeve (36). The lifting brackets (38) are connected to the mounting shell (35) by a telescopic rod (39). A motor guide cylinder (34) for mounting the dual-head motor (33) is provided on the mounting shell (35). The dual-head motor (33) moves up and down inside the motor guide cylinder (34).

3. The apparatus for preparing high-purity lithium fluoride according to claim 2, characterized in that, The telescopic rod (39) is an electric telescopic rod, a hydraulic rod, or a pneumatic rod.

4. The apparatus for preparing high-purity lithium fluoride according to claim 1, characterized in that, The discharge pipe (13) and the return port (15) are connected by a return pipe (6), and the return pipe (6) is also equipped with a return switch valve (7) and a return pump (8).

5. The apparatus for preparing high-purity lithium fluoride according to claim 1, characterized in that, The bottom of the reactor (1) is provided with a frustum portion that cooperates with the isolation cover (31) and a cylindrical portion that cooperates with the grinding mechanism (4). The reactor (1) is provided with an inclined surface, and the discharge pipe (13) is provided at the lowest point of the inclined surface. The bottom of the reactor (1) is also provided with a frame (5).

6. The apparatus for preparing high-purity lithium fluoride according to claim 1, characterized in that, The reactor (1) is made of stainless steel and the inner wall of the reactor (1) is provided with a polytetrafluoroethylene layer.

7. A method for preparing high-purity lithium fluoride, comprising using the apparatus for preparing high-purity lithium fluoride as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Before the reaction, the isolation cover (31) is lowered to the lowest position. The isolation cover (31) divides the interior of the reactor (1) into an upper pre-stirring reaction zone and a lower grinding zone. The rotary stirring mechanism (2) and the spiral stirring blade (25) perform rotation operations. S2: Determine the reaction ratio of lithium carbonate and hydrofluoric acid. Solid lithium carbonate particles and liquid hydrofluoric acid are fed into the reactor (1) through the solid feed pipe (11) and the liquid feed pipe (12) respectively. Under the rotation of the rotary stirring mechanism (2) and the spiral stirring blade (25), lithium carbonate and hydrofluoric acid are mixed and reacted to generate lithium fluoride-hydrofluoric acid-lithium carbonate mixed slurry and hydrofluoric acid and carbon dioxide gas. S3: After the lithium carbonate and hydrofluoric acid have reacted for a period of time, the grinding mechanism is started and the isolation cover (31) is raised to the highest position so that the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry is transported to the grinding mechanism (4) through the gap channel between the isolation cover (31) and the reaction vessel (1) for grinding. The grinding mechanism (4) crushes and grinds the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry. The grinding mechanism (4) adjusts the height of the grinding shaft (43) by adjusting the sleeve (45), thereby adjusting the grinding gap between the grinding roller (42) and the grinding ring (41), and thus adjusting the size of the grinding particles; S4: After the lithium fluoride-hydrofluoric acid-lithium carbonate mixture slurry has entered the grinding mechanism, the isolation cover (31) is lowered to the lowest position again, dividing the interior of the reactor (1) into an upper pre-stirring reaction zone and a lower grinding zone, ensuring that the reaction in the reactor (1) proceeds. The ground reactants return to the upper pre-stirring reaction zone in the reactor (1) for reaction under the action of the discharge pipe (13), reflux pipe (6), reflux switch valve (7) and reflux pump (8). S5: Repeat steps S1-S4 multiple times until lithium carbonate reacts completely to form lithium fluoride.

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