Multistage grinding device for lithium iron phosphate precursor

Abstract

This invention belongs to the field of lithium-ion battery material preparation technology, and particularly relates to a multi-stage grinding device for lithium iron phosphate precursors. Addressing the problems of low grinding efficiency and inability to effectively grind lithium iron phosphate precursors of varying viscosities in existing devices, the following solution is proposed: a grinding jar, and coarse grinding components and fine grinding components arranged vertically. Both the coarse and fine grinding components are connected to the shaft of a grinding rotor. The rotation of the grinding rotor drives the coarse and fine grinding components to operate synchronously. This allows for the coarse grinding of the lithium iron phosphate precursor fed into the jar, followed by fine grinding, forming a multi-stage grinding process to ensure better grinding results. Furthermore, through a combination of vertical layering design and composite grinding, the lithium iron phosphate precursor is progressively refined within a single grinding jar, significantly improving the grinding efficiency and product consistency of the lithium iron phosphate precursor.

Description

Technical Field

[0001] This utility model relates to a grinding device, specifically a multi-stage grinding device for lithium iron phosphate precursors, belonging to the field of lithium-ion battery material preparation technology. Background Technology

[0002] Lithium-ion batteries, as a core technology in today's energy storage field, are widely used in electric vehicles, consumer electronics, and renewable energy storage systems. Their performance hinges on the electrochemical characteristics of the cathode material, and lithium iron phosphate (LFP) has become the mainstream choice for power batteries due to its high safety, long cycle life, and low cost. However, LFP has low ionic conductivity, requiring nano-sizing (particle size ≤200nm) and carbon coating processes to improve its rate performance. This places stringent requirements on the particle size uniformity and morphology control of the precursor material. LFP precursors are typically synthesized using a co-precipitation method with iron, phosphorus, and lithium sources to form FePO4·2H2O precursors, which are then subjected to a high-temperature solid-state reaction to obtain the final product. In this process, the particle size distribution, specific surface area, and particle morphology of the precursor directly determine the electrochemical performance of the finished product. Therefore, grinding the precursor becomes the core process in precursor nano-sizing.

[0003] In the prior art, such as the multi-stage grinding equipment for lithium iron phosphate precursor disclosed in CN219785051U, there are a primary grinding box, a secondary grinding box, a dual filtration unit, grinding media, a stirring mechanism, and a filtration and discharge unit. By setting up two-stage grinding and filtration, the grinding efficiency of the precursor is effectively improved. The addition of a detachable dual filtration unit effectively intercepts zirconium balls and foreign objects mixed in with the precursor. However, in actual use, the existing device requires grinding in the primary grinding box for a period of time before the secondary grinding can be carried out. It is impossible to achieve grinding operations in both grinding boxes at the same time, which leads to a low actual grinding efficiency. Secondly, the grinding method adopted is to crush and grind the material with grinding balls. The grinding product obtained by this method needs to be sieved multiple times to achieve good particle uniformity, and it cannot effectively grind lithium iron phosphate precursors with different viscosities. Utility Model Content

[0004] This invention provides a multi-stage grinding device for lithium iron phosphate precursors to address the problems of low grinding efficiency and inability to effectively grind lithium iron phosphate precursors of different viscosities in existing devices.

[0005] The present invention achieves the above objectives through the following technical solution: a multi-stage grinding device for lithium iron phosphate precursor, comprising a grinding tank, a vertically arranged grinding rod rotatably connected inside the grinding tank, and a coarse grinding component and a fine grinding component distributed vertically inside the grinding tank, both of which are connected to the rod body of the grinding rod.

[0006] The coarse grinding assembly includes an outer grinding disc and an inner grinding disc. The inner grinding disc is coaxially fixedly connected to the shaft of the grinding rotor. The outer grinding disc is fixedly connected to the inner wall of the grinding tank. The inner grinding disc is movably positioned below the outer grinding disc. A variable gap is provided between the outer grinding disc and the inner grinding disc. A screening hood is connected to the bottom of the outer grinding disc. A circulating feeding unit is provided on one side of the screening hood.

[0007] The fine grinding assembly includes a turntable and a fixed ring arranged in an axially offset manner. The turntable is coaxially fixedly connected to the body of the grinding rotor. Several rotor teeth are connected to the outer side of the turntable, and several stator teeth are connected to the inner side wall of the fixed ring. The radial portions of the rotor teeth and stator teeth overlap. An annular clamping seat is fixedly connected to the inner wall of the grinding jar, and the ring body of the fixed ring is movably held in the annular clamping seat.

[0008] As a further embodiment of this utility model: a grinding motor is fixedly connected to the middle part of the top of the grinding tank, the rotating shaft of the grinding motor is fixedly connected to the grinding rod on the same axis, a feed pipe is connected to the top of the grinding tank, and the feed pipe is connected to one side of the grinding motor. A support leg with an inclined arrangement is fixedly connected to the bottom edge of the grinding tank, and a counterweight is fixedly connected inside the bottom of the grinding tank.

[0009] As a further improvement of this utility model: the grinding outer disc has a cooling inner cavity, and the grinding tank body is connected to guide pipes distributed vertically, which are respectively connected to the cooling inner cavity, which is filled with coolant.

[0010] As a further embodiment of this utility model: the interior of the grinding inner disc is provided with a cavity, and a number of annular heat-conducting plates arranged in parallel are embedded in the cavity of the grinding inner disc, and a number of heat dissipation tip protrusions are connected to the lower surface of the annular heat-conducting plates.

[0011] As a further embodiment of this utility model: the screening cover has an inclined shaking screen connected inside, and the bottom end of the screening cover is connected to an elastic docking cover, which is connected to the ring body of the fixed ring.

[0012] The circulating feeding unit includes a large particle collection tank and a vacuum extraction pipe. The large particle collection tank is fixedly connected to the outer wall of the screening hood, and the large particle collection tank is connected to the lower part of the hood where the shaking screen is tilted. The bottom of the large particle collection tank is connected to the vacuum extraction pipe, and the body of the vacuum extraction pipe is connected to a vacuum feeder.

[0013] As a further embodiment of this utility model: several push columns are evenly distributed on the upper and lower sides of the fixed ring. The annular clamping seat is located on both sides of the fixed ring and has a liquid guiding cavity and several push cavities connected to the liquid guiding cavity. The push columns are inserted into the push cavities one by one, and the liquid guiding cavity is filled with hydraulic oil.

[0014] As a further embodiment of this utility model: a hydraulic outer box is fixedly connected to the wall of the grinding tank, a piston plate is movably connected inside the hydraulic outer box, and a threaded rod is rotatably connected inside the hydraulic outer box. The threaded rod passes through the center of the piston plate. A lifting and adjusting motor is fixedly connected to the outer wall of the hydraulic outer box. The rotating shaft of the lifting and adjusting motor is fixedly connected to the threaded rod on the same axis. Hydraulic oil delivery pipes are connected to the upper and lower sides of the hydraulic outer box. One end of each hydraulic oil delivery pipe is connected to the cavity inside the box on both sides of the piston plate. The other end of each hydraulic oil delivery pipe is connected to the liquid guiding cavity opened in the annular clamping seat. Both the hydraulic outer box and the hydraulic oil delivery pipes are filled with hydraulic oil.

[0015] As a further improvement of this utility model: a material collection hopper is also provided inside the grinding tank. The material collection hopper is connected to the bottom of the fixed ring. An ultrasonic vibrating screen is fixedly connected inside the material collection hopper. The bottom end of the material collection hopper is connected to a discharge pipe, and the body of the discharge pipe passes through the bottom end of the grinding tank.

[0016] The beneficial effects of this utility model are:

[0017] 1. The grinding tank of this utility model is equipped with coarse grinding components and fine grinding components arranged vertically. Both coarse grinding components and fine grinding components are connected to the shaft of the grinding rotor. The rotation of the grinding rotor can drive the coarse grinding components and fine grinding components to work synchronously. That is, the lithium iron phosphate precursor delivered into the tank can be coarsely ground first and then finely ground, forming a multi-stage grinding method to ensure a better grinding effect. Furthermore, through the combination of vertical layer design and composite grinding, the lithium iron phosphate precursor is refined step by step in a single grinding tank, which significantly improves the grinding efficiency and product consistency of the lithium iron phosphate precursor.

[0018] 2. The coarse grinding assembly of this utility model includes an outer grinding disc and an inner grinding disc. A variable-pitch gap is provided between the outer grinding disc and the inner grinding disc. A screening cover is connected to the bottom of the outer grinding disc. A circulating feeding unit is provided on one side of the screening cover. When the lithium iron phosphate precursor enters the variable-pitch gap, the relative rotation of the outer grinding disc and the inner grinding disc can achieve the grinding treatment of the lithium iron phosphate precursor when the grinding rod drives the inner grinding disc to rotate. The variable-pitch gap allows the small particles formed after grinding to move downward continuously and be continuously ground, forming a staged grinding process, which can improve the grinding efficiency. After coarse grinding, the lithium iron phosphate precursor will fall directly into the screening cover for screening. Particles that can pass through the screen can fall directly into the fine grinding assembly for further fine grinding treatment, while particles that cannot pass through the screen are circulated and transported to the coarse grinding assembly by the circulating feeding unit for coarse grinding treatment again, forming a cyclic coarse grinding process, which can also improve the coarse grinding efficiency.

[0019] 3. The fine grinding component of this utility model includes a turntable and a stationary ring. Several rotor teeth are connected to the outer side of the turntable, and several stator teeth are connected to the inner sidewall of the stationary ring. The radial portions of the rotor teeth and stator teeth overlap. When the turntable rotates, the trajectory of the rotor teeth and the gap between the stator teeth form a dynamic shearing zone. The staggered tooth design increases the area of ​​the shearing zone, thereby improving grinding efficiency. When the coarsely ground lithium iron phosphate precursor enters the gap between the rotor teeth and stator teeth, it is torn and broken by the shearing force of the high-speed rotating rotor teeth and the reverse resistance of the stator teeth. At the same time, the vortex effect generated by the staggered tooth shape prolongs the residence time of the lithium iron phosphate precursor, improves the grinding uniformity, and achieves fine grinding of the lithium iron phosphate precursor. The stationary ring can be displaced and adjusted within the annular clamping seat, thereby adjusting the axial gap between the rotor teeth and stator teeth to cope with lithium iron phosphate precursors of different viscosities and avoid material blockage or over-grinding. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall appearance and structure of the present utility model;

[0021] Figure 2 This is a schematic diagram of the overall cross-sectional structure of this utility model;

[0022] Figure 3 This is a schematic diagram of the cross-sectional structure of the grinding outer disc of this utility model;

[0023] Figure 4 This is a schematic diagram of the cross-sectional structure of the grinding inner disc of this utility model;

[0024] Figure 5 This is a schematic diagram of the cross-sectional structure of the annular heat-conducting sheet of this utility model;

[0025] Figure 6This is a schematic cross-sectional view of the screening cover and circulating feeding unit of this utility model;

[0026] Figure 7 This is a partial structural diagram of the fine grinding component of this utility model;

[0027] Figure 8 This is a schematic diagram of the cross-sectional structure of the fixed ring, the annular clamping seat, and the hydraulic outer box of this utility model.

[0028] In the diagram: 1. Grinding tank; 11. Feed pipe; 12. Grinding motor; 13. Support leg; 14. Counterweight; 2. Grinding rotor; 3. Grinding outer disc; 31. Cooling inner cavity; 32. Guide pipe; 4. Grinding inner disc; 41. Annular heat-conducting fin; 42. Heat dissipation tip protrusion; 5. Screening cover; 51. Vibrating screen; 52. Large particle collection tank; 53. Vacuum extraction pipe; 54. Vacuum feeder; 55. Flexible docking cover; 6. Turntable; 61. Rotor teeth; 7. Stator ring; 71. Stator teeth; 72. Annular clamping seat; 73. Liquid guiding cavity; 74. Pushing cavity; 75. Pushing column; 76. Hydraulic outer box; 77. Hydraulic oil conveying pipe; 78. Piston plate; 79. Threaded rotor; 710. Lifting adjustment motor; 8. Ultrasonic vibrating screen; 9. Collection hopper; 91. Discharge pipe. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] Example 1

[0031] like Figures 1 to 8 As shown, a multi-stage grinding device for lithium iron phosphate precursor includes a grinding tank 1. A vertically arranged grinding rod 2 is rotatably connected inside the grinding tank 1. The grinding tank 1 also has a coarse grinding component and a fine grinding component distributed vertically. Both the coarse grinding component and the fine grinding component are connected to the rod of the grinding rod 2. The rotation of the grinding rod 2 can drive the coarse grinding component and the fine grinding component to work synchronously. That is, the lithium iron phosphate precursor delivered into the tank can be coarsely ground first and then finely ground, forming a multi-stage grinding method to ensure a better grinding effect. Furthermore, through the combination of vertical layering design and composite grinding, the lithium iron phosphate precursor is refined step by step in a single grinding tank 1, which significantly improves the grinding efficiency and product consistency of the lithium iron phosphate precursor.

[0032] The coarse grinding assembly includes an outer grinding disc 3 and an inner grinding disc 4. The inner grinding disc 4 is coaxially fixedly connected to the shaft of the grinding rotor 2. The outer grinding disc 3 is fixedly connected to the inner wall of the grinding tank 1. The inner grinding disc 4 is movably positioned below the outer grinding disc 3. A variable-pitch gap is provided between the outer grinding disc 3 and the inner grinding disc 4. A screening hood 5 is connected to the bottom end of the outer grinding disc 3. A circulating feeding unit is provided on one side of the screening hood 5. For the lithium iron phosphate precursor entering the variable-pitch gap, when the grinding rotor 2 drives the inner grinding disc 4 to rotate, the relative rotation between the outer grinding disc 3 and the inner grinding disc 4 can be achieved. The lithium iron phosphate precursor is ground using a variable-pitch gap that allows the small particles formed after grinding to continuously move downwards and be ground continuously, forming a staged grinding process that improves grinding efficiency. After coarse grinding, the lithium iron phosphate precursor falls directly into the screening hood 5 for screening. Particles that can pass through the screen can fall directly into the fine grinding assembly for further fine grinding, while particles that cannot pass through the screen are circulated and transported to the coarse grinding assembly by the circulating feeding unit for coarse grinding again, forming a cyclic coarse grinding process that also improves coarse grinding efficiency.

[0033] The fine grinding assembly includes a rotary disk 6 and a fixed ring 7 arranged in an axially staggered configuration. The rotary disk 6 is coaxially fixedly connected to the shaft of the grinding rotor 2. Several rotor teeth 61 are connected to the outer edge of the rotary disk 6, and several stator teeth 71 are connected to the inner wall of the fixed ring 7. The radial portions of the rotor teeth 61 and stator teeth 71 overlap. An annular clamping seat 72 is fixedly connected to the inner wall of the grinding jar 1. The ring body of the fixed ring 7 is movably held within the annular clamping seat 72. When the rotary disk 6 rotates, the trajectory of the rotor teeth 61 and the gap between the stator teeth 71 form a dynamic shearing zone. Furthermore, the staggered tooth design increases the area of ​​the shearing zone, thus improving the grinding efficiency. To improve grinding efficiency, when the coarsely ground lithium iron phosphate precursor enters the gap between the rotor teeth 61 and the stator teeth 71, the particles are torn and broken by the shearing force of the high-speed rotating rotor teeth 61 and the reverse resistance of the stator teeth 71. At the same time, the vortex effect generated by the interlaced teeth prolongs the residence time of the lithium iron phosphate precursor, improves the grinding uniformity, and achieves fine grinding of the lithium iron phosphate precursor. Furthermore, the stator ring 7 can be displaced and adjusted within the annular clamping seat 72, thereby adjusting the axial gap between the rotor teeth 61 and the stator teeth 71 to cope with lithium iron phosphate precursors of different viscosities and avoid material blockage or over-grinding.

[0034] Example 2

[0035] Improvements based on Example 1:

[0036] like Figures 1 to 5As shown, a grinding motor 12 is fixedly connected to the middle part of the top of the grinding tank 1. The rotating shaft of the grinding motor 12 is fixedly connected to the grinding rod 2 along the same axis. The top of the grinding tank 1 is connected to a feed pipe 11, and the feed pipe 11 is located on one side of the grinding motor 12. An inclined support leg 13 is fixedly connected to the bottom edge of the grinding tank 1. A counterweight 14 is fixedly connected inside the bottom of the grinding tank 1. The lithium iron phosphate precursor can be transported into the tank through the feed pipe 11, and the grinding motor 12 provides driving force to the grinding rod 2, thereby enabling the coarse grinding component and the fine grinding component to work synchronously. The grinding tank 1 lowers its center of gravity through the counterweight 14, thereby ensuring that the support leg 13 provides stable support for the grinding tank 1.

[0037] Furthermore, the grinding outer disk 3 has a cooling inner cavity 31. The grinding tank 1 is connected to a guide pipe 32 distributed vertically. The guide pipe 32 is connected to the cooling inner cavity 31. The cooling inner cavity 31 is filled with coolant, which can cool the grinding outer disk 3. Since some particles of lithium iron phosphate precursor are repeatedly ground on the coarse grinding component, the particle temperature is easily raised during grinding. The cooling inner cavity 3 is filled with cooling liquid. It should be noted that the coolant filled in the cooling inner cavity 31 includes, but is not limited to, ethylene glycol solution with a temperature of 10-15℃, to maintain the temperature of lithium iron phosphate precursor not exceeding 60℃ during grinding, so as to avoid irreversible phase transition of the crystal structure of lithium iron phosphate precursor.

[0038] Furthermore, the inner grinding disk 4 has a cavity inside, and several parallel annular heat-conducting fins 41 are embedded in the cavity. The lower surface of the annular heat-conducting fins 41 is connected to several heat dissipation tip protrusions 42. The cavity allows the surface of the annular heat-conducting fins 41 to be exposed on the outside of the inner disk, thereby dissipating the heat generated by the inner grinding disk 4 during the grinding process. The heat is then dissipated through the heat dissipation tip protrusions 42, achieving cooling of the inner grinding disk 4. Combined with the cooling of the outer grinding disk 3, this ensures the temperature stability of the variable gap between the outer grinding disk 3 and the inner grinding disk 4, optimizes the flowability of the lithium iron phosphate precursor, and avoids ineffective cyclic grinding caused by local overheating.

[0039] like Figure 1 , Figure 2 and Figure 6As shown, the screening cover 5 has an inclined shaking screen 51 connected inside. The bottom end of the screening cover 5 is connected to an elastic docking cover 55, which is connected to the ring body of the fixed ring 7. The lithium iron phosphate precursor after coarse grinding can be screened by the shaking screen 51. The lithium iron phosphate precursor particles that meet the grinding standard can fall through the shaking screen 51 to the fine grinding component for further fine grinding. The elastic docking cover 55 can adapt to the position change when the fixed ring 7 moves up and down, ensuring that the falling lithium iron phosphate precursor can completely enter the fine grinding component.

[0040] The circulating feeding unit includes a large particle collection tank 52 and a vacuum extraction pipe 53. The large particle collection tank 52 is fixedly connected to the outer wall of the screening cover 5, and the large particle collection tank 52 is connected to the lower inclined part of the screen body of the screening cover 5 connected to the shaking screen 51. The bottom end of the large particle collection tank 52 is connected to the vacuum extraction pipe 53, and the body of the vacuum extraction pipe 53 is connected to a vacuum feeder 54. This allows the unscreened lithium iron phosphate precursor particles to roll along the inclined direction of the shaking screen 51 and be collected by the large particle collection tank 52. Through the cooperation of the vacuum extraction pipe 53 and the vacuum feeder 54, the lithium iron phosphate precursors that fail to meet the standards are transported back to the coarse grinding component, thus realizing the circulating flow grinding of lithium iron phosphate precursors.

[0041] like Figure 1 , Figure 2 , Figure 7 and Figure 8 As shown, several push pins 75 are evenly distributed on the upper and lower sides of the ring body of the fixed ring 7. The annular clamping seat 72 is located on both sides of the fixed ring 7 and has a liquid guiding cavity 73 and several push cavities 74 connected to the liquid guiding cavity 73. The push pins 75 are inserted into the push cavities 74 one by one. The liquid guiding cavity 73 is filled with hydraulic oil. Through hydraulic action, when the hydraulic oil in the liquid guiding cavity 73 above the fixed ring 7 decreases and the hydraulic oil in the liquid guiding cavity 73 below the fixed ring 7 increases, the hydraulic oil will flow synchronously in multiple liquid guiding cavities 73, which can smoothly push the fixed ring 7 to move upward. Conversely, it will push the fixed ring 7 to move downward, so as to adjust the axial clearance between the rotor teeth 61 and the stator teeth 71.

[0042] Furthermore, a hydraulic outer casing 76 is fixedly connected to the wall of the grinding tank 1. A piston plate 78 is movably connected inside the hydraulic outer casing 76. A threaded rod 79 is also rotatably connected inside the hydraulic outer casing 76. The thread of the threaded rod 79 passes through the center of the piston plate 78. A lifting and adjusting motor 710 is fixedly connected to the outer wall of the hydraulic outer casing 76. The rotating shaft of the lifting and adjusting motor 710 is coaxially fixedly connected to the threaded rod 79. Hydraulic oil delivery pipes 77 are respectively connected to the upper and lower sides of the hydraulic outer casing 76. One of the two hydraulic oil delivery pipes 77... The two ends of the hydraulic oil delivery pipes 77 are respectively connected to the cavities inside the housing on both sides of the piston plate 78, and the other ends of the two hydraulic oil delivery pipes 77 are respectively connected to the liquid guiding cavity 73 opened in the annular clamping seat 72. The hydraulic outer housing 76 and the hydraulic oil delivery pipes 77 are filled with hydraulic oil. The threaded rotating rod 79 can be rotated by the lifting adjustment motor 710, which can make the piston plate 78 move and adjust. That is, the hydraulic oil can flow in opposite directions in the two hydraulic oil delivery pipes 77, which can push the fixed ring 7 to move up or down for adjustment.

[0043] Furthermore, a collection hopper 9 is also provided inside the grinding tank 1. The collection hopper 9 is connected to the bottom of the fixed ring 7. An ultrasonic vibrating screen 8 is fixedly connected inside the collection hopper 9. The bottom end of the collection hopper 9 is connected to a discharge pipe 91, and the body of the discharge pipe 91 penetrates the bottom end of the grinding tank 1. This allows the finely ground lithium iron phosphate precursor to be collected by the collection hopper 9 and concentrated in the ultrasonic vibrating screen 8 for dispersion and vibration. The resulting uniform powder particles fall from the ultrasonic vibrating screen 8 and are discharged through the discharge pipe 91, thus realizing a complete multi-stage grinding process for the lithium iron phosphate precursor.

[0044] Working principle: The rotation of the grinding rod 2 drives the coarse grinding component and the fine grinding component to work synchronously. For the lithium iron phosphate precursor that enters the variable pitch gap, when the grinding rod 2 drives the inner grinding disk 4 to rotate, the relative rotation between the outer grinding disk 3 and the inner grinding disk 4 can achieve the grinding treatment of the lithium iron phosphate precursor. The variable pitch gap allows the small particles formed after grinding to continuously move downward and be continuously ground, forming a staged grinding process, which can improve grinding efficiency. After coarse grinding, the lithium iron phosphate precursor will fall directly into the screening hood 5 for screening. Particles that can pass through the screen can fall directly into the fine grinding component for further fine grinding. The particles that fail to pass the sieve are then circulated to the coarse grinding assembly by the circulating feeding unit for further coarse grinding, forming a cyclic coarse grinding process. When the coarsely ground lithium iron phosphate precursor enters the gap between the rotor teeth 61 and the stator teeth 71, the particles are torn and broken by the shearing force of the high-speed rotating rotor teeth 61 and the reverse resistance of the stator teeth 71. At the same time, the vortex effect generated by the interlaced teeth prolongs the residence time of the lithium iron phosphate precursor, improves the grinding uniformity, and achieves fine grinding of the lithium iron phosphate precursor. The axial gap between the rotor teeth 61 and the stator teeth 71 can be adjusted to cope with lithium iron phosphate precursors of different viscosities, avoiding material blockage or over-grinding.

[0045] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0046] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multi-stage grinding apparatus for lithium iron phosphate precursors, comprising a grinding jar (1), characterized in that: The grinding jar (1) is rotatably connected to a vertically arranged grinding rod (2). The grinding jar (1) is also provided with a coarse grinding component and a fine grinding component distributed vertically. The coarse grinding component and the fine grinding component are both connected to the rod body of the grinding rod (2). The coarse grinding assembly includes an outer grinding disc (3) and an inner grinding disc (4). The inner grinding disc (4) is coaxially fixedly connected to the shaft of the grinding rotating rod (2). The outer grinding disc (3) is fixedly connected to the inner wall of the grinding tank (1). The inner grinding disc (4) is movably placed below the outer grinding disc (3). A variable gap is provided between the outer grinding disc (3) and the inner grinding disc (4). A screening cover (5) is connected to the bottom end of the outer grinding disc (3). A circulating feeding unit is provided on one side of the screening cover (5). The fine grinding assembly includes a turntable (6) and a fixed ring (7) arranged in an axially offset manner. The turntable (6) is coaxially fixedly connected to the rod body of the grinding rotor (2). The outer side of the turntable (6) is connected to a number of rotor teeth (61). The inner side wall of the fixed ring (7) is connected to a number of stator teeth (71). The radial portion of the rotor teeth (61) and the stator teeth (71) overlap. The inner wall of the grinding tank (1) is fixedly connected to an annular clamping seat (72). The ring body of the fixed ring (7) is movably clamped in the annular clamping seat (72).

2. The multi-stage grinding apparatus for lithium iron phosphate precursor according to claim 1, characterized in that: A grinding motor (12) is fixedly connected to the middle part of the top of the grinding tank (1). The rotating shaft of the grinding motor (12) is fixedly connected to the grinding rod (2) on the same axis. The top of the grinding tank (1) is connected to a feed pipe (11), and the feed pipe (11) is located on one side of the grinding motor (12). A support leg (13) is fixedly connected to the bottom edge of the grinding tank (1) in an inclined manner. A counterweight (14) is fixedly connected inside the bottom of the grinding tank (1).

3. The multi-stage grinding apparatus for lithium iron phosphate precursors according to claim 1, characterized in that: The grinding outer disc (3) has a cooling inner cavity (31) on its body. The grinding tank (1) is connected to a guide pipe (32) that is distributed vertically. The guide pipe (32) is connected to the cooling inner cavity (31) respectively. The cooling inner cavity (31) is filled with coolant.

4. The multi-stage grinding apparatus for lithium iron phosphate precursor according to claim 1, characterized in that: The grinding inner disk (4) has a cavity inside, and a number of annular heat-conducting plates (41) arranged in parallel are embedded in the cavity of the grinding inner disk (4), and a number of heat dissipation tip protrusions (42) are connected to the lower surface of the annular heat-conducting plates (41).

5. The multi-stage grinding apparatus for lithium iron phosphate precursor according to claim 1, characterized in that: The screening cover (5) has a shaking screen (51) that is set at an inclination inside the cover. The bottom end of the screening cover (5) is connected to an elastic docking cover (55), and the elastic docking cover (55) is connected to the ring body of the fixed ring (7). The circulating feeding unit includes a large particle collection tank (52) and a vacuum extraction pipe (53). The large particle collection tank (52) is fixedly connected to the outer wall of the screening cover (5), and the large particle collection tank (52) is connected to the lower part of the screen body of the screening cover (5) at the inclined end of the shaking screen (51). The bottom end of the large particle collection tank (52) is connected to the vacuum extraction pipe (53), and the body of the vacuum extraction pipe (53) is connected to a vacuum feeder (54).

6. The multi-stage grinding apparatus for lithium iron phosphate precursor according to claim 1, characterized in that: The fixed ring (7) has several push columns (75) evenly distributed on its upper and lower sides. The annular clamping seat (72) has a liquid guiding cavity (73) and several push cavities (74) connected to the liquid guiding cavity (73) on both sides of the fixed ring (7). The push columns (75) are inserted into the push cavities (74) one by one. The liquid guiding cavity (73) is filled with hydraulic oil.

7. The multi-stage grinding apparatus for lithium iron phosphate precursor according to claim 6, characterized in that: The grinding tank (1) is fixedly connected to a hydraulic outer box (76). A piston plate (78) is movably connected inside the hydraulic outer box (76). A threaded rod (79) is also rotatably connected inside the hydraulic outer box (76). The threaded rod (79) is threaded through the center of the piston plate (78). A lifting adjustment motor (710) is fixedly connected to the outer wall of the hydraulic outer box (76). The rotating shaft of the lifting adjustment motor (710) is fixedly connected to the threaded rod (79) on the same axis. The upper and lower sides of the hydraulic outer box (76) are respectively connected to hydraulic oil delivery pipes (77). One end of the two hydraulic oil delivery pipes (77) is connected to the cavity inside the box on both sides of the piston plate (78). The other end of the two hydraulic oil delivery pipes (77) is connected to the liquid guiding cavity (73) opened by the annular clamping seat (72). The hydraulic outer box (76) and the hydraulic oil delivery pipes (77) are both filled with hydraulic oil.

8. The multi-stage grinding apparatus for lithium iron phosphate precursor according to claim 1, characterized in that: The grinding tank (1) is also provided with a collection hopper (9), which is connected below the fixed ring (7). An ultrasonic vibrating screen (8) is fixedly connected inside the collection hopper (9). The bottom end of the collection hopper (9) is connected to a discharge pipe (91), and the body of the discharge pipe (91) penetrates the bottom end of the grinding tank (1).

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