A purification system and method for lithium dihydrogen phosphate

Abstract

The application provides a purification system and method for lithium dihydrogen phosphate, and relates to the technical field of lithium dihydrogen phosphate preparation. The purification system for lithium dihydrogen phosphate comprises a box, a constant-temperature water source filled in the box, a movable hole formed in the top of the box, a constant-temperature heating device arranged outside the box, and a heating part of the constant-temperature heating device in contact with the constant-temperature water source. A first stirring device is installed on one side of the top of the box. A first driving part is fixedly installed on the top of the box. The purification method for lithium dihydrogen phosphate adopts the purification system for lithium dihydrogen phosphate to purify the crude lithium dihydrogen phosphate. When the docking block is inserted into the docking block, the first driving part can simultaneously drive the rotating operation of the turbulence assembly and the rotating stirring of the stirring rod, so that the circulation turbulence of the constant-temperature water source and the constant-temperature stirring reaction of the material in the barrel are simultaneously realized under the action of the driving structure.

Description

Technical Field

[0001] This invention relates to the field of lithium dihydrogen phosphate preparation technology, and in particular to a purification system and method for lithium dihydrogen phosphate. Background Technology

[0002] Lithium dihydrogen phosphate (LiH2PO4) is a key precursor for lithium-ion battery cathode materials (especially high-density lithium iron phosphate). Its purity, crystallinity, and impurity content directly determine the battery's energy density, cycle life, and safety. It is also widely used in analytical reagents and catalysts. With the market demand for high-purity LiH2PO4 continuing to rise, the demand for LiH2PO4 purification systems and equipment is constantly increasing.

[0003] The purification system used in the existing purification process requires a constant temperature water bath. During the operation of the equipment, the reaction solution needs to be placed inside the constant temperature water bath for constant temperature treatment to maintain a constant reaction temperature. However, the constant temperature water bath is affected by the heat exchange of the material during constant temperature control, resulting in rapid local temperature changes. Since the water bath environment is stagnant, the rate of temperature change and recovery after heat exchange is reduced, which means that the stability of the constant temperature control of the reaction system needs to be further improved.

[0004] Therefore, it is necessary to provide a purification system for lithium dihydrogen phosphate to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a purification system for lithium dihydrogen phosphate, which solves the problem that the stability of the reaction system under isothermal control needs to be further improved in related technologies.

[0006] To solve the above-mentioned technical problems, the present invention provides a purification system for lithium dihydrogen phosphate, comprising:

[0007] The box is filled with a constant temperature water source. The top of the box has an opening for movement. A constant temperature heating device is installed on the outside of the box. The heating part of the constant temperature heating device is in contact with the constant temperature water source.

[0008] A first stirring device is installed on one side of the top of the box body;

[0009] A first driving component is fixedly installed on the top of the housing, and a flow-disrupting component is fixedly provided inside the housing. The first driving component is used to drive the flow-disrupting component to rotate and disrupt the flow.

[0010] The first switching component includes a rotating frame, a material cylinder, and a second driving component. The rotating frame is rotatably mounted inside the housing, and the material cylinder is fixed on the rotating frame. The output end of the first stirring device passes through the housing and is aligned with the rotation range of the material cylinder inlet. The fixing part of the second driving component is fixed to the bottom of the housing, and the drive shaft of the second driving component passes through the housing and is fixedly connected to the rotating frame.

[0011] A mixing assembly, comprising a support plate, a mixing rod, and a docking block, wherein the support plate is fixed inside the material cylinder, the mixing rod passes through the support plate and is rotatably connected, and the docking block is fixed to the top of the mixing rod;

[0012] The switching assembly includes a bracket, a rotating sleeve shaft, a first transmission component, a telescopic component, a connecting plate, and a connecting shaft. The bracket is fixed to the top of the housing. The rotating sleeve shaft is rotatably connected to the bracket. The first transmission component drives the rotating sleeve shaft and the drive shaft of the first drive component. The two ends of the telescopic component are fixedly connected to the housing and the connecting plate. The top of the connecting shaft is rotatably connected to the connecting plate. The bottom of the connecting shaft passes through the rotating sleeve shaft and is connected by a sliding key. A docking block is fixedly provided at the bottom of the connecting shaft. The bottom of the docking block is inserted into the movable hole and aligned with the rotation range of the docking block.

[0013] Preferably, the turbulence component includes a mounting box, a first bevel gear, a propeller blade, and a second bevel gear. The top of the mounting box is fixed to the top wall of the housing. The drive shaft of the first drive unit passes through the housing and the mounting box in sequence and is fixedly connected to the second bevel gear. The shaft end of the propeller blade passes through the mounting box and is fixedly connected to the first bevel gear. The first bevel gear and the second bevel gear are meshed together.

[0014] Preferably, there are two material cylinders, which are evenly arranged in a ring on the rotating frame, and the material cylinders are arranged in a one-to-one correspondence with the stirring assembly.

[0015] Preferably, the bottom of the box is provided with a first liquid outlet pipe and a second liquid outlet pipe, and the input end of the first liquid outlet pipe is aligned with the rotation range of the output end of the material cylinder;

[0016] The purification system for lithium dihydrogen phosphate further includes:

[0017] A second stirring device is installed on the other side of the top of the box body;

[0018] A screw conveyor is fixed on the housing. The input end of the screw conveyor is connected to the first liquid outlet pipe, and the slag output end of the screw conveyor is connected to the input end of the second stirring device.

[0019] The second switching component is disposed inside the box. The second switching component has the same structure as the first switching component. The output end of the second stirring device passes through the box and is aligned with the rotation range of the feed inlet of the second switching component.

[0020] Preferably, a partition is fixed inside the housing, and the partition is disposed between the first switching component and the second switching component.

[0021] Preferably, an exhaust pipe is provided on the top of the housing, and the exhaust pipe is aligned with the rotation range of the feed inlet of the second switching component.

[0022] Preferably, the first driving component is a dual-axis motor, and a synchronization component is connected to the top of the first driving component. The synchronization component includes a first transmission wheel, two second transmission wheels, and a transmission belt. The first transmission wheel is fixed to the rotating shaft of the first driving component, one second transmission wheel is fixed to the driving part of the first stirring device, and the other second transmission wheel is fixed to the driving part of the second stirring device. The transmission belt drives and connects the first transmission wheel and the two second transmission wheels.

[0023] Preferably, the second driving component is a second gear, the second driving component is fixed to the top of the rotating frame shaft, and the first gear is fixed on the connecting shaft;

[0024] When the connecting shaft is fully raised, the first gear meshes with the second gear;

[0025] When the connecting shaft drives the mating block to move downward and remains retracted within the movable hole, the first gear and the second gear remain separated.

[0026] When the docking plug is inserted into the docking card block, the first gear and the second gear remain separated.

[0027] Preferably, the drive unit of the second switching component is connected to the bottom of the rotating frame shaft via a second transmission member.

[0028] This invention also provides a method for purifying lithium dihydrogen phosphate, which uses the aforementioned purification system for lithium dihydrogen phosphate to purify crude lithium dihydrogen phosphate, and includes the following steps:

[0029] Step S1: Crude product dissolution. Add crude lithium dihydrogen phosphate to deionized water and stir until completely dissolved to form a lithium dihydrogen phosphate solution. Keep the solution warm in a water bath at 90~100℃.

[0030] Step S2, ammonia precipitation: Under stirring conditions, ammonia is slowly added dropwise to the solution obtained in step S1 to adjust the pH of the solution to 8-9. At this time, a large amount of white lithium phosphate precipitate is generated. Continue stirring for 10-30 minutes to ensure complete precipitation.

[0031] Step S3, solid-liquid separation: the solid-liquid mixture obtained in step S2 is subjected to solid-liquid separation to obtain lithium phosphate precipitate wet material, and the mother liquor is collected, treated or discharged.

[0032] Step S4, phosphoric acidification: The lithium phosphate precipitate obtained in step S3 is added to deionized water and dispersed by slurrying. Under stirring conditions, phosphoric acid solution is slowly added dropwise for acidification titration until the precipitate is completely dissolved and the solution becomes clear. At this time, the pH of the solution is about 2~3, and lithium dihydrogen phosphate solution is obtained.

[0033] Step S5, Evaporation and Concentration: The lithium dihydrogen phosphate solution obtained in step S4 is heated and evaporated and concentrated until crystals precipitate, to obtain crude lithium dihydrogen phosphate wet material.

[0034] Step S6, low-temperature rinsing: The crude lithium dihydrogen phosphate wet material obtained in step S5 is rapidly rinsed 1 to 3 times with a small amount of pre-cooled deionized water at 0~5℃, and then filtered or centrifuged to obtain purified lithium dihydrogen phosphate wet material.

[0035] Step S7, drying: Place the wet material obtained in step S6 in an oven at 60~110℃ and dry for 4~12 hours to obtain high-purity lithium dihydrogen phosphate product.

[0036] Compared with related technologies, the purification system for lithium dihydrogen phosphate provided by the present invention has the following advantages:

[0037] The telescopic component facilitates switching of the usage state of the docking plug. When the docking plug is separated from the docking card block, the first driving component is only used to drive the rotation of the turbulence component to facilitate the circulation and turbulence of the constant temperature water source in the tank.

[0038] When the docking plug is inserted into the docking card block, the first driving member can simultaneously drive the turbulence component to rotate and the stirring rod to rotate and stir, so that under the action of a driving structure, the circulation turbulence of the constant temperature water source and the constant temperature stirring reaction of the material in the barrel can be realized at the same time. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0040] Figure 1 A three-dimensional diagram of a first embodiment of a purification system for lithium dihydrogen phosphate provided by the present invention;

[0041] Figure 2 for Figure 1 A 3D view of a partial cross-section of the box structure shown;

[0042] Figure 3 for Figure 2 An enlarged schematic diagram of part A shown;

[0043] Figure 4 for Figure 2 The diagram shows the distribution structure of the first and second switching components. Figure 4 (a) in the middle is Figure 2 The top view of the first and second switching components is shown. Figure 4 (b) in the middle is Figure 4 A magnified view of part (a) in the diagram;

[0044] Figure 5 for Figure 2 A schematic diagram of the cross-sectional structure of section BB shown;

[0045] Figure 6 for Figure 4 The diagram in (a) shows the principle of one switching of the barrel station, where, Figure 6 (a) in the diagram shows the alignment and connection between the material cylinder and the first stirring device. Figure 6 (b) in the diagram is a state diagram during the rotation of the barrel. Figure 6 (c) in the diagram shows the alignment of the barrel and the docking block;

[0046] Figure 7 for Figure 6 The adjustment principle diagram of the mating block in state (c) is shown in the figure. Figure 7 (a) is a schematic diagram of the structure in the separated state of the docking insert and the docking card block. Figure 7 (b) is a schematic diagram of the docking block and the docking card block in the docking state;

[0047] Figure 8 A three-dimensional diagram of a second embodiment of a purification system for lithium dihydrogen phosphate provided by the present invention;

[0048] Figure 9 for Figure 8 The diagram shows a partial cross-sectional view of the box.

[0049] Figure 10 for Figure 9 An enlarged schematic diagram of section C shown.

[0050] Explanation of icon numbers:

[0051] 1. Box body; 10. Movable hole; 11. Constant temperature heating device; 12. First liquid outlet pipe; 13. Second liquid outlet pipe; 14. Baffle plate; 15. Exhaust pipe;

[0052] 2. First stirring device;

[0053] 3. Second stirring device;

[0054] 4. Screw conveyor device;

[0055] 5. First drive component; 51. Aerodynamic assembly; 511. Mounting box; 512. First bevel gear; 513. Propeller blade; 514. Second bevel gear; 52. Synchronization assembly; 521. First transmission wheel; 522. Second transmission wheel; 523. Transmission belt;

[0056] 6. First switching component; 61. Rotating frame; 62. Material cylinder; 63. Second driving component;

[0057] 7. Switching component; 71. Bracket; 72. Rotating sleeve shaft; 73. First transmission component; 74. Telescopic component; 75. Connecting plate; 76. Connecting shaft; 761. Dating block; 762. First gear;

[0058] 8. Second switching component; 81. Second transmission component;

[0059] 9. Stirring assembly; 91. Support plate; 92. Stirring rod; 93. Connecting block.

[0060] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0062] This invention provides a purification system for lithium dihydrogen phosphate.

[0063] First embodiment.

[0064] Please see Figures 1 to 4 In this invention, a purification system for lithium dihydrogen phosphate includes:

[0065] Box 1, the box 1 is filled with constant temperature water source, the top of the box 1 is provided with a movable hole 10, and a constant temperature heating device 11 is provided outside the box 1, the heating part of the constant temperature heating device 11 is in contact with the constant temperature water source;

[0066] The first stirring device 2 is installed on one side of the top of the box body 1;

[0067] The first driving component 5 has a fixed part that is fixedly installed on the top of the housing 1. The housing 1 is equipped with a turbulence-disrupting component 51. The first driving component 5 is used to drive the turbulence-disrupting component 51 to rotate and turbulence.

[0068] The first switching component 6 includes a rotating frame 61, a material cylinder 62, and a second driving component 63. The rotating frame 61 is rotatably installed inside the housing 1, and the material cylinder 62 is fixed on the rotating frame 61. The output end of the first stirring device 2 passes through the housing 1 and is aligned with the rotation range of the material cylinder 62's inlet. The fixing part of the second driving component 63 is fixed to the bottom of the housing 1, and the drive shaft of the second driving component 63 passes through the housing 1 and is fixedly connected to the rotating frame 61.

[0069] The stirring assembly 9 includes a support plate 91, a stirring rod 92, and a docking block 93. The support plate 91 is fixed inside the material cylinder 62, the stirring rod 92 passes through the support plate 91 and is rotatably connected, and the docking block 93 is fixed to the top of the stirring rod 92.

[0070] The switching component 7 includes a bracket 71, a rotating sleeve 72, a first transmission component 73, a telescopic component 74, a connecting plate 75, and a connecting shaft 76. The bracket 71 is fixed to the top of the housing 1. The rotating sleeve 72 is rotatably connected to the bracket 71. The first transmission component 73 is tractively connected to the rotating sleeve 72 and the drive shaft of the first drive component 5. The two ends of the telescopic component 74 are fixedly connected to the housing 1 and the connecting plate 75. The top of the connecting shaft 76 is rotatably connected to the connecting plate 75. The bottom of the connecting shaft 76 passes through the rotating sleeve 72 and is connected by a sliding key. A docking block 761 is fixedly provided at the bottom of the connecting shaft 76. The bottom of the docking block 761 is inserted into the movable hole 10 and aligned with the rotation range of the docking block 93.

[0071] In this embodiment, "sliding key connection" means that the connecting shaft 76 can slide up and down relative to the rotating sleeve shaft 72; and when the rotating sleeve shaft 72 rotates, it can drive the connecting shaft 76 to rotate synchronously.

[0072] The housing 1 is equipped with a liquid injection pipe (not shown in the figure) for adding or discharging constant temperature water. The constant temperature water source can be deionized water, which is heated and controlled by the constant temperature heating device 11 to provide support for constant temperature control of the water source.

[0073] The constant temperature heating device 11 adopts existing electric heating equipment for heating and controlling the constant temperature of water source.

[0074] The first stirring device 2 adopts an existing stirred reactor. The first stirring device 2 is equipped with two inlets: one inlet for adding crude lithium dihydrogen phosphate and deionized water, and the other inlet for adding ammonia water dropwise after the crude lithium dihydrogen phosphate solution is obtained. The first stirring device 2 can be optionally equipped with a pH sensor for online pH detection of the mixed solution, depending on the application requirements.

[0075] In this embodiment, the mating block 761 includes two usage states:

[0076] In the separated state, the docking block 761 is completely retracted within the range of the movable hole 10, and the rotation range of the docking block 761, the rotating frame 61, and the material cylinder 62 is staggered, which facilitates the rotation adjustment of the rotating frame 61, and the first driving member 5 facilitates the separate circulation and turbulence of the constant temperature water source.

[0077] In the docking state, the docking plug 761 is inserted and engaged with the docking latch 93 downwards, so that after the material cylinder 62 rotates into the range of the docking plug 761, it can be used for the separate circulation and turbulence of the constant temperature water source and the rotation and stirring operation of the stirring rod 92 by the driving power of the first driving member 5.

[0078] In this embodiment, the first driving component 5 is a motor structure, which is used to directly drive the rotation of the turbulence component 51, so as to provide power for the circulation turbulence of the constant temperature water source.

[0079] The second driving component 63 can be a motor structure, used to directly drive the rotation adjustment of the rotating frame 61, so as to facilitate the rotation of the material cylinder 62 and the switching of work positions. The rotating frame 61 rotates 90° each time.

[0080] In this embodiment, the telescopic member 74 can be any one of an electric telescopic rod, a hydraulic telescopic rod, or a telescopic cylinder, used to directly drive the lifting and lowering adjustment of the connecting plate 75 and the connecting shaft 76, thereby facilitating the switching of the usage state of the docking block 761.

[0081] The telescopic component 74 facilitates the switching of the usage state of the docking plug 761. When the docking plug 761 is separated from the docking block 93, the first driving component 5 is only used to drive the rotation of the turbulence component 51 to facilitate the circulation and turbulence of the constant temperature water source in the box 1.

[0082] When the docking plug 761 is inserted into the docking card 93, the first driving member 5 can simultaneously drive the turbulence component 51 to rotate and the stirring rod 92 to rotate and stir, so that under the action of a driving structure, the circulation turbulence of the constant temperature water source and the constant temperature stirring reaction of the material in the barrel 62 can be realized at the same time.

[0083] In an optional embodiment of this example, the first transmission member 73 consists of two pulleys and a belt. One pulley is fixed to the drive shaft of the first drive member 5, and the other pulley is fixedly connected to the rotating sleeve shaft 72. The belt drives the two pulleys, so that when the drive shaft of the first drive member 5 rotates, the rotating sleeve shaft 72 can be driven to rotate synchronously through the first transmission member 73.

[0084] In another optional embodiment of this example, the first transmission member 73 consists of two sprockets and a chain. One sprocket is fixed to the drive shaft of the first drive member 5, and the other sprocket is fixedly connected to the rotating sleeve shaft 72. The chain drives the two sprockets, so that when the drive shaft of the first drive member 5 rotates, the rotating sleeve shaft 72 can be driven to rotate synchronously through the first transmission member 73.

[0085] Please refer to the following: Figure 2 and Figure 4 In (b), the turbulence assembly 51 includes a mounting box 511, a first bevel gear 512, a propeller blade 513, and a second bevel gear 514. The top of the mounting box 511 is fixed to the top wall of the housing 1. The drive shaft of the first drive member 5 passes through the housing 1 and the mounting box 511 in sequence and is fixedly connected to the second bevel gear 514. The shaft end of the propeller blade 513 passes through the mounting box 511 and is fixedly connected to the first bevel gear 512. The first bevel gear 512 and the second bevel gear 514 are meshed together.

[0086] The propeller blade 513 and the mounting box 511 are rotated and sealed by a mechanical seal structure, which is used to isolate and seal the connection structure between the first bevel gear 512 and the second bevel gear 514 from the constant temperature water source.

[0087] The first bevel gear 512 is connected to the drive shaft of the first drive member 5 through the second bevel gear 514, so that when the first drive member 5 is running, the second bevel gear 514 drives the first bevel gear 512 to rotate synchronously, and the first bevel gear 512 drives the propeller blade 513 to rotate. When the propeller blade 513 rotates, it drives the constant temperature water source to circulate and turbulent along the inner wall of the box 1, so that the temperature distribution of the constant temperature water source is uniform.

[0088] Please refer to the following: Figure 2 and Figure 4 In (a), two material cylinders 62 are provided, and the two material cylinders 62 are evenly arranged in a ring on the rotating frame 61. The material cylinders 62 are arranged in a one-to-one correspondence with the stirring assembly 9.

[0089] By setting two feed cylinders 62, support is provided for subsequent material discharge and mixing.

[0090] Please refer to the following: Figure 2 and Figure 5 The bottom of the housing 1 is provided with a first liquid outlet pipe 12 and a second liquid outlet pipe 13, and the input end of the first liquid outlet pipe 12 is aligned with the rotation range of the output end of the material cylinder 62.

[0091] The purification system for lithium dihydrogen phosphate further includes:

[0092] The second stirring device 3 is installed on the other side of the top of the box 1;

[0093] A screw conveyor 4 is fixed on the housing 1. The input end of the screw conveyor 4 is connected to the first liquid outlet pipe 12, and the slag output end of the screw conveyor 4 is connected to the input end of the second stirring device 3.

[0094] The second switching component 8 is disposed inside the housing 1. The second switching component 8 has the same structure as the first switching component 6. The output end of the second stirring device 3 passes through the housing 1 and is aligned with the rotation range of the feed inlet of the second switching component 8.

[0095] In this embodiment, the arrangement structure of the second switching component 8 is the same as that of the first switching component 6. The first switching component 6 and the second switching component 8 are symmetrically arranged within the constant temperature water source range of the box 1, so that the box 1 can simultaneously provide a constant temperature water source environment for the first switching component 6 and the second switching component 8.

[0096] The difference is that the second switching component 8 does not have a stirring structure inside its barrel.

[0097] In this embodiment, the rotation range of the output end of the first switching component 6 (the outlet of the material cylinder 62) is set to correspond to the input end of the first liquid outlet pipe 12.

[0098] When the output end of the first switching component 6 is misaligned with the input end of the first outlet pipe 12, the output end of the first switching component 6 is in the closed state.

[0099] When the output end of the first switching component 6 is connected to the input end of the first liquid outlet pipe 12, the output end of the first switching component 6 is in the open state, which facilitates the discharge of materials after constant temperature stirring.

[0100] In this embodiment, the rotation range of the output end of the second switching component 8 is set to correspond to the input end of the second liquid outlet pipe 13;

[0101] When the output terminal of the second switching component 8 is misaligned with the input terminal of the second outlet pipe 13, the output terminal of the second switching component 8 is in the closed state.

[0102] When the output end of the second switching component 8 is connected to the input end of the second liquid outlet pipe 13, the output end of the second switching component 8 is in the open state, which facilitates the discharge of the evaporated and concentrated material.

[0103] In this embodiment, the workstation switching of the first switching component 6 and the workstation switching of the second switching component 8 are controlled separately.

[0104] The second stirring device 3 adopts the existing stirring reactor, which is equipped with an independent drive structure and feed pipe to facilitate the addition of deionized water and phosphoric acid solution;

[0105] The first liquid outlet pipe 12 is connected to the output range of the material cylinder 62 and the feed inlet of the screw conveyor 4. The screw conveyor 4 is used to perform solid-liquid separation on the mixed material after processing in the material cylinder 62, and to convey the separated residue upwards to the interior of the second stirring device 3. The tail liquid after separation is discharged separately.

[0106] This allows for both constant-temperature processing of the material within the first switching component 6 and constant-temperature evaporation and concentration of the material within the second switching component 8 within one of the boxes 1.

[0107] After the material is stirred at a constant temperature in the material cylinder 62, the mixture can be separated into solid and liquid by the screw conveyor 4, and the slag is conveyed upwards to the interior of the second stirring device 3 by a screw conveyor.

[0108] Please refer to the following: Figure 2 and Figure 4 In (a), a partition 14 is fixedly provided inside the housing 1, and the partition 14 is disposed between the first switching component 6 and the second switching component 8.

[0109] By providing the partition 14, while the propeller blade 513 drives the constant temperature water source to turbulent flow, it also circulates stably along the inner wall of the box 1, improving the fluidity of the constant temperature water source and making the temperature distribution of the constant temperature water source inside the box 1 more uniform, thus avoiding large temperature differences in different areas inside the box 1.

[0110] Please see Figure 5 The top of the housing 1 is provided with an exhaust pipe 15, which is aligned with the rotation range of the feed inlet of the second switching component 8.

[0111] In this embodiment, the exhaust pipe 15 and the output end of the second stirring device 3 are staggered. When the receiving range of the second switching component 8 is connected to the output end of the second stirring device 3, the receiving range of the second exhaust pipe 15 and the second switching component 8 are staggered to facilitate the feeding of the stirred material in the second stirring device 3.

[0112] When the receiving range of the second switching component 8 is misaligned with the output end of the second stirring device 3, the second exhaust pipe 15 is connected to the receiving range of the second switching component 8 so that the material received in the second switching component 8 can be evaporated and concentrated.

[0113] By providing the exhaust pipe 15 within the rotation range of the second switching component 8, it is convenient to connect the material receiving range of the second switching component 8 with the exhaust pipe 15, thereby facilitating the exhaust of materials within the second switching component 8 during constant-temperature evaporation and concentration.

[0114] In an optional embodiment of this example, three exhaust pipes 15 are provided (not shown in the figure), and the three exhaust pipes 15 are evenly distributed within the rotation range of the feed inlet of the second switching component 8.

[0115] The three exhaust pipes 15 are misaligned with the output pipe of the second stirring device 3. When the receiving range of the second switching component 8 is connected to the second stirring device 3, it is convenient to receive the material after it has been stirred by the second stirring device 3 and maintain it within the constant temperature range of the constant temperature water source.

[0116] When the receiving range of the second switching component 8 is misaligned with the second stirring device 3, the two receiving ranges of the second switching component 8 are respectively connected to the two exhaust pipes 15, which facilitates the evaporation and concentration of the material on the one hand, and facilitates the discharge of the material after evaporation and concentration through the second liquid outlet pipe 13 on the other hand.

[0117] This facilitates the evaporation, concentration, or discharge of materials during the rotation adjustment process of the second switching component 8.

[0118] The working principle of the purification system for lithium dihydrogen phosphate provided in this embodiment is as follows:

[0119] Let us define it as follows: In the initial state, the first stirring device 2 contains a lithium dihydrogen phosphate solution that has been stirred and dissolved in advance, and ammonia water has been added dropwise; the box 1 is filled with a constant temperature water source that has been regulated.

[0120] A1, such as Figure 6 As shown in (a), the rotating frame 61 is first controlled to rotate counterclockwise by the second driving component 63. The rotating frame 61 drives the two material cylinders 62 to rotate. The input end of one of the material cylinders 62 is connected to the output end of the first stirring device 2. The output end of the first stirring device 2 is automatically opened and the mixture of lithium dihydrogen phosphate solution and ammonia water is injected into the material cylinder 62, so that the mixture reacts at a constant temperature.

[0121] A2, combined Figure 6 (a) to Figure 6 (b) to Figure 6 (c) In the workstation switching, the second drive unit 63 is started. The second drive unit 63 drives the rotating frame 61 to rotate counterclockwise by 90°. The rotating frame 61 drives the two material cylinders 62 to rotate synchronously, so that the input end of the material cylinder 62 is misaligned with the output end of the first stirring device 2, so that the output end of the first stirring device 2 is automatically closed.

[0122] The input end of the material cylinder 62 is vertically connected to the movable hole 10, and the docking block 761 and the docking clip 93 are vertically aligned.

[0123] A3, usage status switching, see reference. Figure 7 (a) to Figure 7In (b), the telescopic component 74 is activated, and the telescopic component 74 controls the connecting plate 75 to move down. The connecting plate 75 drives the connecting shaft 76 and the docking block 761 to move down synchronously. The docking block 761 engages with the docking latch 93, so that the docking block 761 switches from the separated state to the docking state.

[0124] A4, synchronous operation, start the first drive component 5, the first drive component 5 drives the first bevel gear 512 to rotate through the second bevel gear 514, the first bevel gear 512 drives the propeller blade 513 to rotate, the propeller blade 513 drives the constant temperature water source circulation turbulence in the box 1;

[0125] On the other hand, the first driving member 5 drives the rotating sleeve shaft 72 to rotate through the first transmission member 73. The rotating sleeve shaft 72 drives the connecting shaft 76 to rotate. The connecting shaft 76 drives the docking block 93 to rotate synchronously through the docking plug 761. The docking block 93 drives the stirring rod 92 to rotate. The stirring rod 92 stirs the material in the material cylinder 62.

[0126] After the material reaction at a constant temperature is completed in the material cylinder 62, the telescopic component 74 controls the docking block 761 to reset from the docking state to the separation state.

[0127] A5, material separation and transmission: the rotating frame 61 and the material cylinder 62 are rotated as a whole by the second driving component 63, so that the output end of the material cylinder 62 is connected to the first liquid outlet pipe 12. The material in the material cylinder 62 is transported to the screw conveyor 4 through the first liquid outlet pipe 12. The screw conveyor 4 performs solid-liquid separation on the material. The separated residue is spirally conveyed upward to the interior of the second stirring device 3.

[0128] A6. Add deionized water to the second stirring device 3, and stir and mix the slag and deionized water. Under stirring conditions, slowly add phosphoric acid solution for acidification titration.

[0129] After the mixing is completed, the receiving range of the second switching component 8 is aligned and connected with the output end of the second stirring device 3, so that the mixed material in the second stirring device 3 is injected into the interior of the second switching component 8;

[0130] Then, the receiving range is controlled by the second switching component 8 to align and connect with the exhaust pipe 15, and the output end of the second stirring device 3 is automatically closed to facilitate the evaporation and concentration of the material;

[0131] A7. After the material in the second switching component 8 is evaporated and concentrated, the output end of the second switching component 8 is connected to the second liquid outlet pipe 13 so that the product after evaporation and concentration is discharged through the second liquid outlet pipe 13.

[0132] Second embodiment.

[0133] Please refer to the following: Figures 8 to 10 Based on the purification system for lithium dihydrogen phosphate provided in the first embodiment of the present invention, the second embodiment of the present invention proposes another purification system for lithium dihydrogen phosphate. The second embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the separate implementation of the first embodiment.

[0134] Specifically, the second embodiment of the present invention provides a purification system for lithium dihydrogen phosphate, wherein the first driving component 5 adopts a dual-axis motor, and a synchronization component 52 is connected to the top of the first driving component 5. The synchronization component 52 includes a first transmission wheel 521, two second transmission wheels 522, and a transmission belt 523. The first transmission wheel 521 is fixed to the rotating shaft of the first driving component 5, one second transmission wheel 522 is fixed to the driving part of the first stirring device 2, and the other second transmission wheel 522 is fixed to the driving part of the second stirring device 3. The transmission belt 523 drives the first transmission wheel 521 and the two second transmission wheels 522.

[0135] In this embodiment, the first transmission wheel 521 is a sprocket structure, the two second transmission wheels 522 are sprocket structures, and the transmission belt 523 is a chain structure. This allows the first driving member 5 to drive the first transmission wheel 521 to rotate, while the first transmission wheel 521 drives the two second transmission wheels 522 to rotate synchronously via the transmission belt 523.

[0136] The driving parts of the first stirring device 2 and the second stirring device 3 are connected to the first driving wheel 521 through two second driving wheels 522 and the driving belt 523;

[0137] When the docking block 761 is in the separated state, during the operation of the first driving component 5, it can not only drive the propeller blade 513 to rotate, but also simultaneously drive the first stirring device 2 and the second stirring device 3 to rotate and stir.

[0138] When the docking block 761 is in the docking state, during the operation of the first driving component 5, it can not only drive the propeller blade 513 to rotate, but also drive the first stirring device 2 and the second stirring device 3 to rotate synchronously, and also drive the stirring rod 92 to rotate and stir synchronously, reducing power consumption, realizing multiple uses of one machine, and meeting the requirements of energy-saving and environmentally friendly operation.

[0139] Preferably, the second driving component 63 may not be a motor structure.

[0140] Please refer to it again. Figure 8 The second driving component 63 is a second gear, and the second driving component 63 is fixed to the top of the rotating shaft of the rotating frame 61. The first gear 762 is fixed on the connecting shaft 76.

[0141] When the connecting shaft 76 is fully raised, the first gear 762 meshes with the second gear;

[0142] When the connecting shaft 76 drives the docking block 761 to move down and remains retracted within the movable hole 10, the first gear 762 and the second gear remain separated.

[0143] When the docking plug 761 is inserted into the docking card block 93, the first gear 762 and the second gear remain separated.

[0144] In this embodiment, after the telescopic member 74 drives the connecting plate 75 and the connecting shaft 76 to move completely upward, the connecting shaft 76 can also drive the first gear 762 to engage with the second driving member 63, so that the connecting shaft 76 can also drive the rotating frame 61 to rotate and adjust when rotating.

[0145] When the docking block 761 is in the separated state, the telescopic member 74 can also control the docking and meshing between the first gear 762 and the second drive member 63, so that the first drive member 5 can control the first stirring device 2 and the second stirring device 3 to rotate and stir synchronously while controlling the rotation of the propeller blade 513 to turbulence, and can also control the rotation adjustment of the rotating frame 61 synchronously to facilitate the switching of the work position of the material cylinder 62.

[0146] When the docking block 761 is in the docking state, the telescopic member 74 can control the separation and avoidance between the first gear 762 and the second drive member 63, so that the first drive member 5 can control the first stirring device 2 and the second stirring device 3 to rotate and stir synchronously while controlling the propeller blade 513 to rotate and turbulence, and can also control the stirring rod 92 to rotate and stir simultaneously, which facilitates the stirring and processing of the material in the material cylinder 62 after the position of the material cylinder 62 is switched.

[0147] Please refer to the following: Figures 8 to 9 The drive unit of the second switching component 8 is connected to the bottom of the rotating shaft of the rotating frame 61 via the second transmission component 81.

[0148] In an optional embodiment of this example, the second transmission component 81 is a sprocket transmission structure, consisting of two sprockets and a chain. One sprocket is fixedly connected to the bottom of the rotating shaft of the rotating frame 61, and the other sprocket is fixedly connected to the bottom of the corresponding rotating shaft of the second switching component 8, so that the first switching component 6 and the second switching component 8 can rotate and switch synchronously.

[0149] The second transmission component 81 is used to connect the rotating frame 61 and the second switching component 8, so that the second switching component 8 can rotate and switch synchronously during the process of the rotating frame 61 driving the material cylinder 62 to rotate and switch, so as to facilitate the synchronous rotation and switching of the two sets of storage structures.

[0150] The working principle of a purification system for lithium dihydrogen phosphate provided in this embodiment is as follows:

[0151] Step B1: When the station switching of the material cylinder 62 is not required, the connecting plate 75, the connecting shaft 76 and the first gear 762 are first moved down by the telescopic member 74, so that the first gear 762 is separated from the second driving member 63, and the docking block 761 is kept retracted within the range of the movable hole 10.

[0152] When the first driving component 5 is activated, the first driving component 5 drives the turbulence component 51 to rotate and turbulence, and at the same time drives the first transmission wheel 521 to rotate. The first transmission wheel 521 drives two second transmission wheels 522 to rotate synchronously through the transmission belt 523. One of the second transmission wheels 522 provides power for the stirring operation of the first stirring device 2, and the other second transmission wheel 522 provides power for the stirring operation of the second stirring device 3.

[0153] Step B2: When it is necessary to switch the working position of the material cylinder 62, the connecting plate 75, the connecting shaft 76 and the first gear 762 are first moved upward by the telescopic member 74, so that the first gear 762 and the second driving member 63 are engaged. During this period, the docking block 761 is kept retracted within the range of the movable hole 10.

[0154] Then, the first drive component 5 is activated. While the first drive component 5 drives the turbulence component 51 to rotate and turbulence, it also provides rotational stirring power to the first stirring device 2 and the second stirring device 3. It can also drive the rotating sleeve shaft 72 to rotate through the first transmission component 73. The rotating sleeve shaft 72 drives the connecting shaft 76 to rotate synchronously. The connecting shaft 76 drives the first gear 762 to rotate. The first gear 762 drives the second drive component 63 to rotate. The second drive component 63 drives the rotating frame 61 and the material cylinder 62 to rotate as a whole until the rotating frame 61 rotates 90°, realizing a one-time switching of the material cylinder 62, so as to use the driving power of the first drive component 5 to realize the switching of the material cylinder 62's position.

[0155] The telescopic component 74 enables the switching of the working state of the connecting shaft 76, so that the first driving component 5 can be used for circulating and turbulent flow of constant temperature water source, provide power for the rotation of the first stirring device 2 and the second stirring device 3, provide power for the rotation of the stirring rod 92 according to the needs of use, and provide power for the switching of the working position of the material cylinder 62 according to the needs of use.

[0156] In this embodiment, the purification system for lithium dihydrogen phosphate is mainly used for the processing and preparation of lithium-ion battery cathode materials, that is, the purification process of lithium dihydrogen phosphate, which is part of the battery material processing technology.

[0157] The present invention also provides a method for purifying lithium dihydrogen phosphate.

[0158] The purification method for lithium dihydrogen phosphate, using the aforementioned purification system for lithium dihydrogen phosphate, includes the following steps:

[0159] Step S1: Crude product dissolution. Add crude lithium dihydrogen phosphate to deionized water and stir until completely dissolved to form a lithium dihydrogen phosphate solution. Keep the solution warm in a water bath at 90~100℃.

[0160] Step S2, ammonia precipitation: Under stirring conditions, ammonia is slowly added dropwise to the solution obtained in step S1 to adjust the pH of the solution to 8-9. At this time, a large amount of white lithium phosphate precipitate is generated. Continue stirring for 10-30 minutes to ensure complete precipitation.

[0161] Step S3, solid-liquid separation: the solid-liquid mixture obtained in step S2 is subjected to solid-liquid separation to obtain lithium phosphate precipitate wet material, and the mother liquor is collected, treated or discharged.

[0162] Step S4, phosphoric acidification: The lithium phosphate precipitate obtained in step S3 is added to deionized water and dispersed by slurrying. Under stirring conditions, phosphoric acid solution is slowly added dropwise for acidification titration until the precipitate is completely dissolved and the solution becomes clear. At this time, the pH of the solution is about 2~3, and lithium dihydrogen phosphate solution is obtained.

[0163] Step S5, Evaporation and Concentration: The lithium dihydrogen phosphate solution obtained in step S4 is heated and evaporated and concentrated until crystals precipitate, to obtain crude lithium dihydrogen phosphate wet material.

[0164] Step S6, low-temperature rinsing: The crude lithium dihydrogen phosphate wet material obtained in step S5 is rapidly rinsed 1 to 3 times with a small amount of pre-cooled deionized water at 0~5℃, and then filtered or centrifuged to obtain purified lithium dihydrogen phosphate wet material.

[0165] Step S7, drying: Place the wet material obtained in step S6 in an oven at 60~110℃ and dry for 4~12 hours to obtain high-purity lithium dihydrogen phosphate product.

[0166] Preferably, in step S2, the mass concentration of ammonia is 10%~25%, and the reaction temperature is 90℃.

[0167] Preferably, in step S2, the pH of the reaction is controlled to be 8.3~8.8.

[0168] Preferably, in step S4, the mass concentration of the phosphoric acid solution is 20%~50%, and the acidification titration temperature is room temperature.

[0169] Preferably, in step S4, the pH at the endpoint of the acidification titration is controlled to be 2.3 to 2.6.

[0170] Preferably, in step S5, the evaporation and concentration temperature is 80~100℃.

[0171] Preferably, in step S6, the temperature of the low-temperature rinsing water is 0~2℃.

[0172] Preferably, in step S6, the low-temperature rinsing is performed 1 to 3 times, and the amount of water used each time is 0.5 to 2 times the mass of the wet material.

[0173] Preferably, in step S7, the drying temperature is 80~90℃ and the drying time is 4~6 hours.

[0174] Preferably, the method further includes: if the purity of the product does not meet the requirements after one purification, the product obtained in step S6 can be used as the raw material for step S1 to repeat the S1~S7 operations, and each cycle can further reduce the impurity content.

[0175] Beneficial effects:

[0176] Crude lithium dihydrogen phosphate was dissolved in water, utilizing its high solubility to completely dissolve the crystals and release impurities into the liquid phase. Subsequently, ammonia was used to adjust the pH of the solution to 8-9. At this point, lithium ions and phosphate ions combine under weakly alkaline conditions to form lithium phosphate precipitate, while a large amount of water-soluble impurities (such as potassium chloride) are released. + Na + SO4 2- The lithium phosphate precipitate remains in the mother liquor, and initial impurity removal is achieved through solid-liquid separation. Then, the obtained lithium phosphate precipitate is acidified and titrated with phosphoric acid solution, and the endpoint pH is controlled at 2-3 to completely dissolve the lithium phosphate and convert it into lithium dihydrogen phosphate solution. After that, it is evaporated and concentrated to obtain crude lithium dihydrogen phosphate crystals. Finally, the crystals are rinsed with a small amount of cold water at 0-5°C to remove residual impurities attached to the surface by short-time low-temperature rinsing, and high-purity lithium dihydrogen phosphate product is obtained.

[0177] Case 1:

[0178] A method for purifying lithium dihydrogen phosphate includes the following steps:

[0179] S1: Dissolve the crude product. Take 100g of the crude lithium dihydrogen phosphate to be purified (purity approximately 96.5%, main impurity is potassium). + Na + SO4 2- Add 300 mL of deionized water, stir until completely dissolved, and keep warm at 95°C;

[0180] S2: Ammonia precipitation: Slowly add 20% ammonia solution under stirring to adjust the pH of the solution to 8.8. At this point, a large amount of white lithium phosphate precipitate is generated. Continue to keep the solution warm and stir for 20 minutes.

[0181] S3: Solid-liquid separation, the reaction solution is filtered under vacuum while hot to obtain wet lithium phosphate precipitate, and the mother liquor is collected;

[0182] S4: Phosphoric acidification: Lithium phosphate precipitate was added to 200 mL of deionized water and dispersed by slurrying. Under stirring at room temperature, a 30% phosphoric acid solution was slowly added dropwise until the precipitate was completely dissolved and the solution became clear. The pH of the solution was measured to be 2.8.

[0183] S5: Evaporation and concentration. The solution is heated to 80°C and evaporated and concentrated until a large amount of crystals precipitate out, to obtain crude lithium dihydrogen phosphate wet material.

[0184] S6: Low-temperature rinsing, the wet material is rinsed twice with 100mL of deionized water pre-cooled to 0℃, and then separated by vacuum filtration;

[0185] S7: Drying. Place the filter cake in a forced-air drying oven and dry at 80°C for 4 hours to obtain the purified lithium dihydrogen phosphate product.

[0186] Case 2:

[0187] A method for purifying lithium dihydrogen phosphate includes the following steps:

[0188] S1: Crude product dissolution: Take 100g of crude lithium dihydrogen phosphate to be purified (same as in Example 1), add 300mL of deionized water to dissolve, and keep warm at 90℃;

[0189] S2: Ammonia precipitation, slowly add 25% ammonia to adjust the pH to about 8.5, lithium phosphate precipitate is generated, keep warm and stir for 15 minutes;

[0190] S3: Solid-liquid separation, centrifugation to obtain lithium phosphate precipitate;

[0191] S4: Phosphoric acidification. After slurrying the precipitate, add 40% phosphoric acid solution dropwise at room temperature until the precipitate is completely dissolved. The endpoint pH is 2.5.

[0192] S5: Evaporation and concentration, the solution is evaporated and concentrated at 90℃ until crystals precipitate;

[0193] S6: Low-temperature rinsing, rinse once quickly with 80mL of 2℃ cold deionized water, and then filter;

[0194] S7: Drying, drying at 90℃ for 4 hours, to obtain lithium dihydrogen phosphate product.

[0195] Case 3 (Secondary Cycle Purification):

[0196] To further verify the effectiveness of the cyclic purification, crude lithium dihydrogen phosphate with lower purity was purified:

[0197] S1: Crude product dissolution: Take 50g of lithium dihydrogen phosphate with a purity of 86.3% (the main impurities are sodium, potassium and sulfate), add 150mL of deionized water to dissolve, and keep warm at 90℃;

[0198] S2: Ammonia water precipitation, add 20% ammonia water dropwise to adjust pH to 8.8, keep warm and stir for 20 minutes;

[0199] S3: Solid-liquid separation, filtration to obtain lithium phosphate precipitate;

[0200] S4: Phosphoric acidification, after pulping, add 30% phosphoric acid dropwise until the precipitate dissolves, the endpoint pH is 2.5;

[0201] S5: Evaporation and concentration, evaporation and concentration at 90℃ until crystallization occurs;

[0202] S6: Low-temperature rinsing, rinse twice with 40mL of 0℃ cold deionized water;

[0203] S7: Drying at 90℃ for 6 hours yields a lithium dihydrogen phosphate product with a purity of 97.98%. Steps S1 through S7 are then repeated to obtain a further purified lithium dihydrogen phosphate battery-grade product.

[0204] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A purification system for lithium dihydrogen phosphate, characterized in that, include: The box is filled with a constant temperature water source. The top of the box has an opening for movement. A constant temperature heating device is installed on the outside of the box. The heating part of the constant temperature heating device is in contact with the constant temperature water source. A first stirring device is installed on one side of the top of the box body; A first driving component is fixedly installed on the top of the housing, and a flow-disrupting component is fixedly provided inside the housing. The first driving component is used to drive the flow-disrupting component to rotate and disrupt the flow. The first switching component includes a rotating frame, a material cylinder, and a second driving component. The rotating frame is rotatably mounted inside the housing, and the material cylinder is fixed on the rotating frame. The output end of the first stirring device passes through the housing and is aligned with the rotation range of the material cylinder inlet. The fixing part of the second driving component is fixed to the bottom of the housing, and the drive shaft of the second driving component passes through the housing and is fixedly connected to the rotating frame. A mixing assembly, comprising a support plate, a mixing rod, and a docking block, wherein the support plate is fixed inside the material cylinder, the mixing rod passes through the support plate and is rotatably connected, and the docking block is fixed to the top of the mixing rod; The switching assembly includes a bracket, a rotating sleeve shaft, a first transmission component, a telescopic component, a connecting plate, and a connecting shaft. The bracket is fixed to the top of the housing. The rotating sleeve shaft is rotatably connected to the bracket. The first transmission component drives the rotating sleeve shaft and the drive shaft of the first drive component. The two ends of the telescopic component are fixedly connected to the housing and the connecting plate. The top of the connecting shaft is rotatably connected to the connecting plate. The bottom of the connecting shaft passes through the rotating sleeve shaft and is connected by a sliding key. A docking block is fixedly provided at the bottom of the connecting shaft. The bottom of the docking block is inserted into the movable hole and aligned with the rotation range of the docking block.

2. The purification system for lithium dihydrogen phosphate according to claim 1, characterized in that, The turbulence-causing component includes a mounting box, a first bevel gear, a propeller blade, and a second bevel gear. The top of the mounting box is fixed to the top wall of the housing. The drive shaft of the first drive unit passes through the housing and the mounting box in sequence and is fixedly connected to the second bevel gear. The shaft end of the propeller blade passes through the mounting box and is fixedly connected to the first bevel gear. The first bevel gear and the second bevel gear are meshed together.

3. The purification system for lithium dihydrogen phosphate according to claim 2, characterized in that, There are two material cylinders, which are evenly arranged in a ring on the rotating frame, and the material cylinders are arranged in a one-to-one correspondence with the stirring assembly.

4. The purification system for lithium dihydrogen phosphate according to claim 3, characterized in that, The bottom of the box is provided with a first liquid outlet pipe and a second liquid outlet pipe, and the input end of the first liquid outlet pipe is aligned with the rotation range of the output end of the material cylinder. The purification system for lithium dihydrogen phosphate further includes: A second stirring device is installed on the other side of the top of the box body; A screw conveyor is fixed on the housing. The input end of the screw conveyor is connected to the first liquid outlet pipe, and the slag output end of the screw conveyor is connected to the input end of the second stirring device. The second switching component is disposed inside the box. The second switching component has the same structure as the first switching component. The output end of the second stirring device passes through the box and is aligned with the rotation range of the feed inlet of the second switching component.

5. The purification system for lithium dihydrogen phosphate according to claim 4, characterized in that, A partition is fixed inside the box, and the partition is disposed between the first switching component and the second switching component.

6. The purification system for lithium dihydrogen phosphate according to claim 5, characterized in that, The top of the housing is provided with an exhaust pipe, which is aligned with the rotation range of the feed inlet of the second switching component.

7. The purification system for lithium dihydrogen phosphate according to claim 6, characterized in that, The first driving component uses a dual-axis motor. A synchronization component is connected to the top of the first driving component. The synchronization component includes a first transmission wheel, two second transmission wheels, and a transmission belt. The first transmission wheel is fixed to the rotating shaft of the first driving component. One of the second transmission wheels is fixed to the driving part of the first stirring device, and the other second transmission wheel is fixed to the driving part of the second stirring device. The transmission belt drives and connects the first transmission wheel and the two second transmission wheels.

8. A purification system for lithium dihydrogen phosphate according to claim 7, characterized in that, The second driving component is a second gear, which is fixed to the top of the rotating frame shaft, and the first gear is fixed on the connecting shaft; When the connecting shaft is fully raised, the first gear meshes with the second gear; When the connecting shaft drives the mating block to move downward and remains retracted within the movable hole, the first gear and the second gear remain separated. When the docking plug is inserted into the docking card block, the first gear and the second gear remain separated.

9. A purification system for lithium dihydrogen phosphate according to claim 8, characterized in that, The drive unit of the second switching component is connected to the bottom of the rotating frame shaft via a second transmission member.

10. A method for purifying lithium dihydrogen phosphate, comprising purifying crude lithium dihydrogen phosphate using the purification system for lithium dihydrogen phosphate as described in any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Crude product dissolution. Add crude lithium dihydrogen phosphate to deionized water and stir until completely dissolved to form a lithium dihydrogen phosphate solution. Keep the solution warm in a water bath at 90~100℃. Step S2, ammonia precipitation: Under stirring conditions, ammonia is slowly added dropwise to the solution obtained in step S1 to adjust the pH of the solution to 8-9. At this time, a large amount of white lithium phosphate precipitate is generated. Continue stirring for 10-30 minutes to ensure complete precipitation. Step S3, solid-liquid separation: the solid-liquid mixture obtained in step S2 is subjected to solid-liquid separation to obtain lithium phosphate precipitate wet material, and the mother liquor is collected, treated or discharged. Step S4, phosphoric acidification: The lithium phosphate precipitate obtained in step S3 is added to deionized water and dispersed by slurrying. Under stirring conditions, phosphoric acid solution is slowly added dropwise for acidification titration until the precipitate is completely dissolved and the solution becomes clear. At this time, the pH of the solution is about 2~3, and lithium dihydrogen phosphate solution is obtained. Step S5, Evaporation and Concentration: The lithium dihydrogen phosphate solution obtained in step S4 is heated and evaporated and concentrated until crystals precipitate, to obtain crude lithium dihydrogen phosphate wet material. Step S6, low-temperature rinsing: The crude lithium dihydrogen phosphate wet material obtained in step S5 is rapidly rinsed 1 to 3 times with a small amount of pre-cooled deionized water at 0~5℃, and then filtered or centrifuged to obtain purified lithium dihydrogen phosphate wet material. Step S7, drying: Place the wet material obtained in step S6 in an oven at 60~110℃ and dry for 4~12 hours to obtain high-purity lithium dihydrogen phosphate product.

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