Sanding device, process, control system and control terminal of lithium iron phosphate production line

Abstract

The invention belongs to the field of lithium iron phosphate preparation, and relates to a sanding device, process, control system and control terminal of a lithium iron phosphate production line. The sanding device comprises two first material storage tanks and at least two second material storage tanks, the first material storage tanks are used for injecting materials to be ground, and the second material storage tanks are used for injecting roughly ground materials; an input end and an output end are arranged on each of the coarse grinding sand mill and the fine grinding sand mills; the first switching device is used for communicating the input end of the rough grinding sand mill with one first storage tank and communicating and exchanging the output end of the rough grinding sand mill with the other first storage tank; and the second switching device is used for communicating the input ends and the output ends of all the fine grinding sand mills with the selected second storage tank in all the second storage tanks. The particle size distribution of lithium iron phosphate can be obviously improved, excessive grinding is avoided, and the grinding efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium iron phosphate preparation, and in particular relates to a sand grinding device, process, control system and control terminal of a lithium iron phosphate production line. Background Art

[0002] In the production process of lithium iron phosphate, the sand grinding process is a key link, which directly affects the particle size distribution, tap density and final electrochemical properties of the material.

[0003] When the material is sanded by the traditional sanding process, the particle size distribution of lithium iron phosphate is uneven and over-grinding occurs. The uneven particle size distribution will affect the electrochemical properties of the material, such as the diffusion coefficient of lithium ions and the discharge voltage platform of the battery; over-grinding will not only reduce the utilization rate of raw materials and low grinding efficiency, but also may generate unnecessary heat energy, affecting the stability and safety of the material. Summary of the invention

[0004] The object of the present invention is to provide a sand grinding device, process, control system and control terminal for a lithium iron phosphate production line, which can make the particle size distribution of lithium iron phosphate uniform, avoid over-grinding and improve grinding efficiency.

[0005] The above-mentioned purpose is achieved by the following technical solutions. A first aspect of the present invention provides a sand grinding device for a lithium iron phosphate production line, comprising: Two first storage tanks and at least two second storage tanks, the first storage tanks are used to inject materials to be ground, and the second storage tanks are used to inject coarsely ground materials, and the first storage tanks and the second storage tanks are both provided with stirring devices; A coarse grinding sand mill and a plurality of fine grinding sand mills, wherein the coarse grinding sand mill and the fine grinding sand mill are both provided with an input end and an output end; A first switching device, the first switching device is used to connect the input end of the coarse grinding sand mill to one of the first material storage tanks and the output end to another of the first material storage tanks, and the two switching devices are interoperable; The second switching device is used to connect the input end and the output end of all the fine grinding sand mills to the second storage tank selected from all the second storage tanks.

[0006] In some embodiments, the first material storage tank is provided with a first discharge port, a first feed port and a second feed port, and the first feed port is used to inject the material to be ground; the second material storage tank is provided with a third feed port, a fourth feed port and a second discharge port, and the third feed port is used to inject the coarsely ground material; The input end of the coarse grinding sand mill is connected to the first discharge port of the first storage tank, and the output end is connected to the second feed port of the first storage tank; The input end and the output end of the fine grinding sand mill are respectively connected to the second discharge port and the fourth feed port of the second storage tank.

[0007] In some embodiments, a first discharge valve is provided on the pipeline connected to the first discharge port, a first feed valve is provided on the pipeline connected to the second feed port, and all the first discharge valves and all the first feed valves form the first switching device; A second discharge valve is provided on the pipeline connected to the second discharge port, and a second feed valve is provided on the pipeline connected to the fourth feed port. All the second discharge valves and all the second feed valves form the second switching device.

[0008] In some embodiments, the grinding medium of the coarse grinding sand mill is zirconium beads with a particle size of 0.8 mm, and the grinding medium of the fine grinding sand mill is zirconium beads with a particle size of 100 um.

[0009] In some embodiments, a sampling hand valve for sampling and testing is provided on the pipeline connected to the second discharge port.

[0010] A second aspect of the present invention provides a lithium iron phosphate production line device, comprising: A premixing device, any one of the above-mentioned sand grinding devices, an iron removal device and a finished product device connected in sequence.

[0011] A third aspect of the present invention provides a sand grinding process for a lithium iron phosphate production line, comprising: injecting the material to be ground into the selected first storage tank; Input the material in the selected first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material after the coarse grinding sand mill into another first storage tank. When all the materials in the selected first storage tank are emptied, input the material in the other first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material after the coarse grinding sand mill into the selected first storage tank. When all the materials in the other first storage tank are emptied, the current round of coarse grinding is completed and the next round of coarse grinding is carried out until the preset coarse grinding termination condition is reached; Injecting the material in the first storage tank into the selected second storage tank; The material in the selected second storage tank is input into the fine grinding sand mill for fine grinding, and the material ground by the fine grinding sand mill flows back to the selected second storage tank. When it is determined that the particle size of the material in the selected second storage tank meets the preset particle size requirement, the material in the selected second storage tank is output and another second storage tank is selected to start the next round of fine grinding.

[0012] In some embodiments, determining whether the particle size of the material in the selected second storage tank meets the preset particle size requirement includes: Using a laser particle size analyzer to analyze the particle size of the material in the selected second storage tank to obtain particle size distribution data; Determine whether the particle size distribution data meets the preset particle size requirements.

[0013] In some embodiments, zirconium beads with a particle size of 0.8 mm are used to coarsely grind the material in the coarse grinding sand mill, and zirconium beads with a particle size of 100 um are used to finely grind the material in the fine grinding sand mill.

[0014] In some embodiments, it also includes: Use sensors to obtain grinding parameters in real time; According to the grinding parameters, at least one of the filling amount of the grinding medium, the grinding linear speed, and the material flow rate is adjusted.

[0015] In some embodiments, the sensor includes a temperature sensor. When it is detected that the temperature of the material exceeds a set threshold, water is injected into the interlayer of the coarse grinding mill and / or the fine grinding mill and the linear speed of the coarse grinding mill and / or the fine grinding mill is reduced.

[0016] A fourth aspect of the present invention provides a control system for a lithium iron phosphate production line, comprising: An injection unit, the injection unit is used to inject the material to be ground into a first storage tank selected from the two first storage tanks and to inject the material in the first storage tank into the second storage tank; A coarse grinding unit, the coarse grinding unit is used to input the material in the selected first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material ground by the coarse grinding sand mill into another first storage tank. When all the materials in the selected first storage tank are emptied, the material in the other first storage tank is input into the coarse grinding sand mill for coarse grinding, and inject the material ground by the coarse grinding sand mill into the selected first storage tank. When all the materials in the other first storage tank are emptied, the current round of coarse grinding is completed and the next round of coarse grinding is carried out until a preset coarse grinding termination condition is reached; A fine grinding unit is used to input the material in the selected second storage tank into a fine grinding sand mill for fine grinding. The material ground by the fine grinding sand mill flows back to the selected second storage tank. When it is determined that the particle size of the material in the selected second storage tank meets the preset particle size requirement, the material in the selected second storage tank is output and another second storage tank is selected to start the next round of fine grinding.

[0017] A fifth aspect of the present invention provides a control terminal for a lithium iron phosphate production line, the control terminal comprising a memory, a processor, and a control program for the lithium iron phosphate production line stored in the memory and executable on the processor, wherein the control program for the lithium iron phosphate production line implements any one of the steps of the sanding process of the above-mentioned lithium iron phosphate production line when executed by the processor.

[0018] The technical solution provided by the present invention has the following advantages and effects: By first performing coarse grinding and then fine grinding, during the coarse grinding, two first storage tanks are connected in series for circulation, and during the fine grinding, several fine grinding sand mills are used for single tank circulation, which can significantly improve the particle size distribution of lithium iron phosphate, avoid excessive grinding, and improve grinding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of a lithium iron phosphate production line device according to an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of a premixing device of an embodiment; Figure 3 for Figure 1 A schematic diagram of a rough grinding device of an embodiment; Figure 4 for Figure 1 A schematic diagram of a fine grinding device according to an embodiment; Figure 5 for Figure 1 Schematic diagram of the iron removal device and finished product device of the embodiment; Figure 6 It is a flow chart of the sand grinding process of the lithium iron phosphate production line according to an embodiment of the present invention; Figure 7 for Figure 6 Schematic diagram of particle size distribution data obtained in Example.

[0020] Description of reference numerals: 100, premixing device, 200, sand milling device, 210, coarse grinding device, 220, fine grinding device, 300, iron removal device, 400, finished product device, 1. Premixing tank, 1a. Dispersing motor, 1b. Stirring motor, 1c. Weighing module, 2. Discharge valve, 3. Rotor pump, 4. Feed valve, 5. The first storage tank, 5a. The first discharge port, 5b. The first feed port, 5c. The second feed port, 6. The first feed valve, 7. The first feed valve, 8. The feed valve, 9. The first storage tank, 9a. The first discharge port, 9b. The first feed port, 9c. The second feed port, 10. The first discharge valve, 11. The first discharge valve, 12. The filter assembly, 13. The rotor pump, 14. The coarse grinding sand mill, 15. The discharge valve, 16. The discharge valve, 17. The feed valve, 18. The second feed valve, 19. The feed valve, 20. The second feed valve, 21. The feed valve, 22. The second feed valve, 23, second storage tank, 23a, second discharge port, 23b, third feed port, 23c, fourth feed port, 24, second storage tank, 24a, second discharge port, 24b, third feed port, 24c, fourth feed port, 25, second storage tank, 25a, second discharge port, 25b, third feed port, 25c, fourth feed port, 26. Second discharge valve, 27. Second discharge valve, 28. Second discharge valve, 29. Sampling hand valve, 30. Sampling hand valve, 31. Sampling hand valve, 32. Rotor pump, 33. Filter assembly, 34. Discharge valve, 35. Fine grinding sand mill, 36. Filter assembly, 37. Discharge valve, 38. Fine grinding sand mill, 39. Discharge valve, 40. Fine grinding sand mill, 41. Filter assembly, 42. Feed valve, 43. Feed valve, 44. Feed valve, 45. Feed valve, 46. Iron removal tank, 47. Iron removal tank, 48. Finished product tank, 49. Discharge valve, 50. Discharge valve, 51. Discharge valve, 52. Finished product tank, 53. Discharge valve, 54. Filter assembly, 55. Filter assembly. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present invention, specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0022] Unless otherwise specified or defined, the "first, second..." used in this article is merely used to distinguish names and does not represent a specific quantity or order.

[0023] Unless specifically stated or defined otherwise, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] It should be noted that, in this document, “fixed to” or “connected to” may mean directly fixing or connecting to an element, or indirectly fixing or connecting to an element.

[0025] In the production process of lithium iron phosphate, the traditional sand grinding process leads to uneven particle size distribution of lithium iron phosphate and the problem of over-grinding. The present invention optimizes the traditional grinding process, first performs coarse grinding and then fine grinding, adopts a double-tank series mechanism for cyclic coarse grinding, and adopts a single-tank circulation mechanism for cyclic fine grinding, and further determines suitable grinding media and grinding parameters, such as grinding time, grinding linear speed, particle size and filling amount of grinding media, etc., which can significantly improve the particle size distribution of lithium iron phosphate, avoid over-grinding, and improve grinding efficiency.

[0026] Figure 1 This is a schematic diagram of the lithium iron phosphate production line device of this embodiment. It mainly includes a premixing device 100 connected by a pipeline, a sand milling device 200, an iron removal device 300 and a finished product device 400. The premixing device 100 is used to mix the raw materials to form the material to be ground, the sand milling device 200 is used to sand the material to be ground to form the sanded material, the iron removal device 300 is used to remove the iron from the sanded material to obtain the finished product, and the finished product device 400 is used to store the finished product. The finished product is then subjected to subsequent treatments such as spray drying. It should be noted that although this embodiment adopts a pipeline connection, it is not limited to a pipeline connection, and an AGV trolley or other transportation equipment can also be used to transport materials within each device or between devices.

[0027] Figure 2 Schematic diagram of the premixing device of this embodiment. The premixing device 100 includes a premixing tank 1, a discharge valve 2 and a rotor pump 3. The premixing tank 1 is equipped with two dispersion motors 1a to disperse the raw materials (such as iron phosphate and lithium carbonate), and is also equipped with a stirring motor 1b to stir the materials evenly. A weighing module 1c is also provided to weigh the materials. After the materials in the premixing tank 1 are stirred evenly, the materials to be ground are formed, and then the discharge valve 2 is opened, the rotor pump 3 is started, and the materials to be ground are driven into the sand mill 200. The specific process is: after the raw materials are added to the premixing tank 1, the dispersion motor 1a is turned on, and the speed of the dispersion motor 1a is set to 12M / S, the stirring motor 1b is turned on, and the speed of the stirring motor 1b is set to 50rpm. After running for 60 minutes, the discharge valve 2 is opened, the rotor pump 3 is started, and the materials to be ground are driven into the sand mill 200.

[0028] The sand mill 200 includes a coarse grinding device 210 and a fine grinding device 220. The coarse grinding device 210 performs coarse grinding on the material to be ground, and then the material is pumped into the fine grinding device 220 for fine grinding through a rotor pump.

[0029] Figure 3 The schematic diagram of the coarse grinding device of this embodiment is shown in FIG. The coarse grinding device 210 mainly includes a first material storage tank (5, 9), which is also called a coarse grinding tank, and is used to inject the material to be ground. The first material storage tank is equipped with a stirring device, such as a stirring motor, which is used to stir the material while injecting it so that the material is evenly distributed.

[0030] The first material storage tank 5 is provided with a first discharge port 5a, a first feed port 5b and a second feed port 5c. A feed valve 4 is provided on the pipeline connected to the first feed port 5b. When the first material storage tank 5 needs to receive the material to be ground in the premixing tank 1, the discharge valve 2 and the feed valve 4 are opened, and the rotor pump 3 is turned on, so that the material to be ground can be injected into the first material storage tank 5. A first discharge valve 10 is provided on the pipeline connected to the first discharge port 5a. The first discharge port 5a is connected to the rotor pump 13, and is also connected to the input end of the coarse grinding sand mill 14. A filter assembly 12 is provided on the pipeline connected to the input end of the coarse grinding sand mill 14. The second feed port 5c is connected to the output end of the coarse grinding sand mill 14, and the connected pipeline is provided with a first feed valve 6, a discharge valve 16 and a discharge valve 15.

[0031] The first material storage tank 9 is provided with a first discharge port 9a, a first feed port 9b and a second feed port 9c. A feed valve 8 is provided on the pipeline connected to the first feed port 9b. When the first material storage tank 9 needs to receive the material to be ground in the premixing tank 1, the discharge valve 2 and the feed valve 8 are opened, and the rotor pump 3 is turned on, so that the material to be ground can be injected into the first material storage tank 9. A first discharge valve 11 is provided on the pipeline connected to the first discharge port 9a. The first discharge port 9a is connected to the rotor pump 13 and is also connected to the input end of the coarse grinding sand mill 14. The second feed port 9c is connected to the output end of the coarse grinding sand mill 14, and the connected pipeline is provided with a first feed valve 7, a discharge valve 16 and a discharge valve 15.

[0032] When the first discharge valve 10 is opened and the first discharge valve 11 is closed, the input end of the coarse grinding sand mill 14 is connected to the first storage tank 5; when the first discharge valve 10 is closed and the first discharge valve 11 is opened, the input end of the coarse grinding sand mill 14 is connected to the first storage tank 9.

[0033] Open the discharge valve 15 and the discharge valve 16. When the first feed valve 6 is opened and the first feed valve 7 is closed, the output end of the coarse grinding sand mill 14 is connected to the first storage tank 5; when the first feed valve 6 is closed and the first feed valve 7 is opened, the output end of the coarse grinding sand mill 14 is connected to the first storage tank 9.

[0034] Therefore, all the first discharge valves (10, 11) and all the first feed valves (6, 7) form a first switching device, which is used to connect the input end of the rough grinding sand mill 14 to a first storage tank and the output end to another first storage tank and can be switched, that is, it can be switched in two states: state one, the input end of the rough grinding sand mill 14 is connected to the first storage tank 5, and the output end is connected to the first storage tank 9; state two, the input end of the rough grinding sand mill 14 is connected to the first storage tank 9, and the output end is connected to the first storage tank 5. This mechanism is called double tank series connection. By connecting two first storage tanks in series for rough grinding and switching the flow direction of the material in the two first storage tanks, the efficiency of rough grinding can be improved compared to performing cyclic rough grinding in one storage tank, and the particle size of the material after rough grinding is more uniform.

[0035] In this embodiment, the first storage tank is a 20m³ coarse grinding tank equipped with a weighing module and a stirring device, and the coarse grinding sand mill is a 1000L coarse grinding sand mill. The filter assembly 12 includes a diaphragm pump, a 50-mesh filter, and a 12000GS iron remover. Exemplarily, the specific process of coarse grinding is: Open the feed valve 4, pump the material in the premix tank 1 into the first storage tank 5 through the rotor pump 3 and start the stirring motor, set the speed of the stirring motor to 30rpm, start weighing and metering, stop the rotor pump 3 when the material reaches the set value, and close the feed valve 4. Open the first discharge valve 10, and the material passes through the filter assembly 12 and enters the coarse grinding sand mill 14 for coarse grinding. The grinding medium in the coarse grinding sand mill 14 is zirconium beads. Since the goal of coarse grinding is to remove the rough layer on the surface of the material and reduce the original particle size of the material, zirconium beads with a particle size of 0.8mm are used in the coarse grinding sand mill 14. After the material is ground in the sand mill for about 20 minutes, open the discharge valve 15, the discharge valve 16 and the first feed valve 7, and the ground material enters the first storage tank 9, and turn on the stirring motor on the first storage tank 9, set the speed of the stirring motor to 30rpm, until the material in the first storage tank 5 is emptied. Then open the first discharge valve 11, close the first discharge valve 10, and the material enters the coarse grinding sand mill 14 again. After grinding in the coarse grinding sand mill 14 for about 20 minutes, open the discharge valve 15, the discharge valve 16 and the first feed valve 6, and the ground material enters the first storage tank 5 until the material in the first storage tank 9 is emptied, completing the current round of coarse grinding, that is, completing a cycle. The entire coarse grinding process needs to be repeated many times until the preset coarse grinding termination condition (for example, the particle size reaches the required target value) is reached, and then the rotor pump 13 is started to pump the material into the fine grinding device. It should be noted that the first storage tank 9 can also be selected first to inject the material to be ground in the premixing tank 1, that is, open the feed valve 8, and pump the material in the premixing tank 1 into the first storage tank 9 through the rotor pump 3.

[0036] Figure 4Schematic diagram of the fine grinding device of this embodiment. In order to improve the grinding efficiency and make the particle size distribution of lithium iron phosphate more uniform, the fine grinding device 220 includes at least two second storage tanks. The second storage tanks are used to inject the coarsely ground materials. Each second storage tank is provided with a stirring device (such as a stirring motor) for stirring when injecting the material. By using multiple second storage tanks, when one of the second storage tanks is subjected to single-tank cycle fine grinding, the other second storage tanks can receive the materials pumped into the coarse grinding device 210 through the rotor pump 13. In this embodiment, three second storage tanks (23, 24, 25) are provided.

[0037] Each second storage tank is provided with a third feed port, a fourth feed port and a second discharge port. The coarsely ground material is injected through the third feed port, and the second discharge port and the fourth feed port are connected to the fine grinding sand mill. The number of fine grinding sand mills can be set accordingly according to the process requirements. Generally, the more the number of fine grinding sand mills, the higher the efficiency of fine grinding. In this embodiment, fine grinding sand mills (35, 38, 40) are provided.

[0038] Specifically, the second material storage tank 23 is provided with a second discharge port 23a, a third feed port 23b and a fourth feed port 23c. A feed valve 17 is provided on the pipeline connected to the third feed port 23b. When the second material storage tank 23 needs to receive the coarsely ground material, the feed valve 17 is opened and the rotor pump 13 is turned on to inject the coarsely ground material into the second material storage tank 23. A second discharge valve 26 is provided on the pipeline connected to the second discharge port 23a. The second discharge port 23a is connected to the rotor pump 32, and is also connected to the input ends of the fine grinding sand mill 35, the fine grinding sand mill 38, and the fine grinding sand mill 40. The pipelines connected to the input ends of the fine grinding sand mill 35, the fine grinding sand mill 38, and the fine grinding sand mill 40 are respectively provided with filter components 33, filter components 36, and filter components 41. The fourth feed port 23c is connected to the output ends of the fine grinding mill 35, the fine grinding mill 38 and the fine grinding mill 40 at the same time. The connecting pipeline is provided with a second feed valve 18 and a discharge valve 34 on the output end connecting pipeline of the fine grinding mill 35, a discharge valve 37 on the output end connecting pipeline of the fine grinding mill 38, and a discharge valve 39 on the output end connecting pipeline of the fine grinding mill 40.

[0039] The second material storage tank 24 is provided with a second discharge port 24a, a third feed port 24b and a fourth feed port 24c. A feed valve 19 is provided on the pipeline connected to the third feed port 24b. When the second material storage tank 24 needs to receive the coarsely ground material, the feed valve 19 is opened and the rotor pump 13 is turned on to inject the coarsely ground material into the second material storage tank 24. A second discharge valve 27 is provided on the pipeline connected to the second discharge port 24a. The second discharge port 24a is connected to the rotor pump 32, and is also connected to the input ends of the fine grinding sand mill 35, the fine grinding sand mill 38, and the fine grinding sand mill 40. The fourth feed port 24c is connected to the output ends of the fine grinding mill 35, the fine grinding mill 38 and the fine grinding mill 40 at the same time. The connecting pipeline is provided with a second feed valve 20 and a discharge valve 34 on the output end connecting pipeline of the fine grinding mill 35, a discharge valve 37 on the output end connecting pipeline of the fine grinding mill 38, and a discharge valve 39 on the output end connecting pipeline of the fine grinding mill 40.

[0040] The second material storage tank 25 is provided with a second discharge port 25a, a third feed port 25b and a fourth feed port 25c. A feed valve 21 is provided on the pipeline connected to the third feed port 25b. When the second material storage tank 25 needs to receive the coarsely ground material, the feed valve 21 is opened and the rotor pump 13 is turned on to inject the coarsely ground material into the second material storage tank 25. A second discharge valve 28 is provided on the pipeline connected to the second discharge port 25a. The second discharge port 25a is connected to the rotor pump 32, and is also connected to the input ends of the fine grinding sand mill 35, the fine grinding sand mill 38, and the fine grinding sand mill 40. The fourth feed port 25c is connected to the output ends of the fine grinding mill 35, the fine grinding mill 38 and the fine grinding mill 40 at the same time. The connecting pipeline is provided with a second feed valve 22 and a discharge valve 34 on the output end connecting pipeline of the fine grinding mill 35, a discharge valve 37 on the output end connecting pipeline of the fine grinding mill 38, and a discharge valve 39 on the output end connecting pipeline of the fine grinding mill 40.

[0041] When the second discharge valve 26 is opened and the second discharge valve 27 and the second discharge valve 28 are closed, the input end of the fine grinding sand grinder (35, 385, 40) is connected to the second storage tank 23; similarly, the operation of connecting to the second storage tank 24 or the second storage tank 25 is similar to the operation of connecting to the second storage tank 23.

[0042] The discharge valve 34, the discharge valve 37 and the discharge valve 39 are opened. When the second feed valve 18 is opened and the second feed valve 20 and the second feed valve 22 are closed, the output end of the coarse grinding sand mill (35, 38, 40) is connected to the second storage tank 23; when the second feed valve 20 is opened and the second feed valve 18 and the second feed valve 22 are closed, the output end of the coarse grinding sand mill (35, 38, 40) is connected to the second storage tank 24; when the second feed valve 22 is opened and the second feed valve 18 and the second feed valve 20 are closed, the output end of the coarse grinding sand mill (35, 38, 40) is connected to the second storage tank 25.

[0043] Therefore, all the second discharge valves (26, 27, 28) and all the second feed valves (18, 20, 22) form a second switching device, which is used to connect the input end and the output end of the rough grinding sand mill (35, 38, 40) to a selected second storage tank, and finely grind the material in the selected second storage tank. During fine grinding, the material ground by the fine grinding sand mill flows back to the selected second storage tank. This mechanism is called a single tank cycle. And, for example, when it is selected to finely grind the material in the second storage tank 23, the second storage tank 24 and the second storage tank 25 can receive the material pumped in by the rough grinding device 210 or pump the material in the second storage tank that meets the preset particle size requirements into the iron removal device 300 through the rotor pump 32. In this embodiment, a sampling hand valve 29 is provided on the pipeline connected to the second material outlet 23a, a sampling hand valve 30 is provided on the pipeline connected to the second material outlet 24a, and a sampling hand valve 31 is provided on the pipeline connected to the second material outlet 25a. The material in the corresponding second material storage tank can be sampled through the sampling hand valve, so as to detect the particle size of the material and determine whether the particle size meets the preset particle size requirement. When it is determined that the material in the selected second material storage tank 23 meets the preset particle size requirement, the input end and the output end of the coarse grinding sand mill (35, 38, 40) are uniformly connected to the second material storage tank 24 or the second material storage tank 25 through the second switching device.

[0044] By adopting a single tank circulation mechanism for fine grinding, the particle size of the material after fine grinding can be made more uniform, and multiple second storage tanks are provided to improve the efficiency of fine grinding.

[0045] In this embodiment, the second storage tank (23, 24, 25) is a 20m³ fine grinding tank equipped with a weighing module and a stirring device, and the fine grinding sand mill (35, 38, 40) has a capacity of 800L. The filter assembly (33, 36, 41) includes a diaphragm pump, a 500-mesh filter, and a 12000GS iron remover. Exemplarily, the specific process of fine grinding is: The rotor pump 13 is turned on, and the feed valve 17, feed valve 19, and feed valve 21 are opened at the same time. The coarsely ground materials enter the second fine grinding tank 23, the second fine grinding tank 24, and the second fine grinding tank 25 at the same time. The stirring motors of the three second fine grinding tanks are started at the same time, and the speed of the stirring motor is set to 50rpm. Then the second discharge valve 26 is opened, and the materials enter the fine grinding sand mill 35 through the filter component 33, enter the fine grinding sand mill 38 through the filter component 36, and enter the fine grinding sand mill 40 through the filter component 41, and then fine grinding begins. In order to achieve finer grinding, the grinding medium used is a zirconium bead with a particle size of 100um. The particle size of the grinding medium is smaller than that of the coarse grinding stage, which can improve the uniformity and depth of grinding and achieve a predetermined particle size distribution. After the fine grinding sand mill grinds the materials for 30 minutes, the discharge valve (34, 37, 39) is opened. When the materials in the second fine grinding tank 23 are finely ground, the second feed valve 18 is opened to start a single tank cycle. Finally, sampling is performed through the sampling hand valve 29 to detect whether the particle size meets the requirements. When the material particle size meets the requirements, it is pumped out to the iron removal device 30 through the rotor pump 32. The grinding process of the other two second fine grinding tanks is the same as above.

[0046] In some embodiments, the first switching device and the second switching device further include a control panel, and the first switching device and / or the second switching device are automatically enabled by the control panel.

[0047] Figure 5 Schematic diagram of the iron removal device and finished product device of this embodiment. The iron removal device 300 includes a feed valve 42, a feed valve 43, an iron removal tank 46 with a capacity of 20m³ and equipped with a weighing module and a stirring motor, an iron removal tank 47 with a capacity of 20m³ and equipped with a weighing module and a stirring motor, a discharge valve 49, a discharge valve 50, a filter assembly 54 and a filter assembly 55. The filter assembly 54 and the filter assembly 55 include a diaphragm pump, a 1500 mesh filter and a 12000GS iron remover.

[0048] The finished product device 400 includes a feed valve 44, a feed valve 45, a finished product tank 46 with a capacity of 20m³ and equipped with a weighing module and a stirring motor, a finished product tank 52 with a capacity of 20m³ and equipped with a weighing module and a stirring motor, a discharge valve 51 and a discharge valve 53.

[0049] The process of iron removal and finished product storage is as follows: start the rotor pump 32, the material enters the iron removal tank 46 and the iron removal tank 47, start the stirring motor, and set the stirring motor speed to 20rpm. Open the discharge valve 49 and the discharge valve 50, the material passes through the filter component 54 and then circulates for sampling. After the material meets the standard, it enters the finished product tank (48, 52) for buffering, waiting to enter the next spraying process. The iron removal process and finished product storage are conventional means in this field and will not be repeated here.

[0050] In summary, by first connecting two tanks in series for coarse grinding and then circulating a single tank for fine grinding, the grinding efficiency and consistency of particle size distribution can be greatly improved. Multiple storage tanks are used for both coarse grinding and fine grinding. The coarse grinding sand mill and the fine grinding sand mill are connected to different storage tanks through a switching device composed of a feed valve and a discharge valve. The operation is simple, the production efficiency is high, and the grinding can be dispersed and ground efficiently and quickly, with good results.

[0051] Based on the concept of the present invention of first connecting two tanks in series for rough grinding and then circulating a single tank for fine grinding, the present invention also provides a sand grinding process for a lithium iron phosphate production line, which can be deployed on a control terminal of a lithium iron phosphate production line to control the sand grinding process of the lithium iron phosphate production line. Figure 6 As shown, the specific steps include: Step S100: injecting the material to be ground into a selected first storage tank; The first storage tank is used to receive the material to be ground, such as the material after premixing. The material to be ground can be injected into the selected first storage tank by means of AGV trolley, pipeline transportation, etc. A stirring motor and a weighing module can be set in the first storage tank to stir while injecting to make the material more uniform. When the weight displayed by the weighing module reaches the preset weight, the AGV trolley can be removed or the feed valve can be closed to stop the injection.

[0052] Step S200: inputting the material in the selected first storage tank into the coarse grinding sand mill for coarse grinding, and injecting the material after the coarse grinding sand mill is injected into another first storage tank. When all the materials in the selected first storage tank are emptied, inputting the material in the other first storage tank into the coarse grinding sand mill for coarse grinding, and injecting the material after the coarse grinding sand mill is injected into the selected first storage tank. When all the materials in the other first storage tank are emptied, the current round of coarse grinding is completed and the next round of coarse grinding is carried out until the preset coarse grinding termination condition is reached; By inputting the material of one of the two first storage tanks into the coarse grinding sand mill, and the other first storage tank receives the material ground by the coarse grinding sand mill, the two tanks are connected in series, and the input and output can be swapped between the two first storage tanks, which can improve the grinding efficiency and the consistency of the particle size distribution. When switching the input and output between the two first storage tanks, a combination of a feed valve and a discharge valve can be used to achieve this. For specific details, please refer to the content of the above-mentioned sand milling device, which will not be repeated here.

[0053] The particle size of the grinding media in the coarse grinding sand mill determines the number of contact points between it and the material. Media with smaller particle sizes have more contact points under the same volume, which can theoretically improve grinding efficiency. However, for large particle materials, larger particle size grinding media may be required to provide sufficient impact force.

[0054] Table 1 Several common grinding media experimental parameters As can be seen from Table 1, zirconia beads are the best choice for grinding media, and their hardness and wear resistance are better than other media. Therefore, the grinding media in the rough grinding sand mill are zirconia beads. Since the goal of rough grinding is to remove the rough layer on the surface of the material and reduce the original particle size of the material, 0.8mm zirconia beads are used as the grinding media.

[0055] Step S300: injecting the material in the first storage tank into the selected second storage tank; The second storage tank is used to receive the material after the rough grinding in step S200. Similar to step S100, the material in the first storage tank can be injected into the selected second storage tank by means of AGV trolley, pipeline, etc.

[0056] Step S400: input the material in the selected second storage tank into the fine grinding sand mill for fine grinding, and the material ground by the fine grinding sand mill flows back to the selected second storage tank. When it is determined that the particle size of the material in the selected second storage tank meets the preset particle size requirement, the material in the selected second storage tank is output and another second storage tank is selected to start the next round of fine grinding.

[0057] When fine grinding the material in the selected second storage tank, unlike coarse grinding, a single tank circulation method is adopted, that is, the material in the second storage tank is input into the fine grinding sand mill, and the material ground by the fine grinding sand mill flows back into the second storage tank until the particle size meets the preset particle size requirements. For specific details, please refer to the contents of the above-mentioned sand milling device, which will not be repeated here. Single tank circulation during fine grinding and the use of multiple fine grinding sand mills for fine grinding at the same time can significantly improve the grinding efficiency and make the particle size distribution of lithium iron phosphate uniform.

[0058] In order to achieve finer grinding, this embodiment uses zirconium beads with a particle size of 100um as the grinding medium of the fine grinding sand mill to improve the uniformity and depth of grinding and achieve a predetermined particle size distribution. A stirring motor is also set in the second storage tank, which can stir while injecting materials to improve the uniformity of grinding.

[0059] When determining whether the particle size of the material in the selected second storage tank meets the preset particle size requirement, a laser particle size analyzer is used to analyze the particle size of the material in the selected second storage tank to obtain the following: Figure 7 The particle size distribution data shown is then used to determine whether the particle size distribution data meets the preset particle size requirements, for example: whether the proportion of data in the particle size range of 0.8 to 1.2 um (micrometers) in the particle size distribution data is greater than 80%.

[0060] In some embodiments, sensors (such as temperature sensors, pressure sensors, flow sensors, motor speed sensors, etc.) can also be used to obtain grinding parameters in real time, and then one or more of the filling amount of the grinding medium, the grinding linear speed, and the material flow rate can be adjusted in real time according to the grinding parameters. The grinding parameters mainly include flow rate, temperature, material viscosity, and linear speed of the sand mill.

[0061] Among them, flow rate affects product fineness, output and particle size distribution. In continuous grinding process, the absolute value of flow rate and output is equal. In cycle grinding, because the material is cycled and ground many times, only a part of the flow rate is produced as product in each cycle. Output is the flow rate divided by the number of cycles. That is, output = flow rate × That is, the flow rate in the continuous grinding process is equal to the output, while the output in the circulating grinding process is the flow rate. (n is the number of cycles).

[0062] The linear speed of a sand mill refers to the speed of the grinding medium relative to the direction of movement of the grinding medium during the grinding process, usually measured in meters per second (m / s). The linear speed directly affects the kinetic energy intensity applied by the grinding medium to the material particles, thereby affecting the grinding efficiency and product fineness. The linear speed affects the kinetic energy intensity applied by the grinding medium to the material particles, generally 8-15m / s. The linear speed calculation formula is: Where: LV is the linear velocity, usually in meters per second (m / s), w is the angular velocity, in radians per second (rad / s), which can be converted from the rotational speed (RPM), that is: , where r is the radius of the grinding medium in meters (m). If the diameter (D) of the grinding medium is given, since the diameter is twice the radius, the formula can be written as: , Taking out the constants in the above formula, we get: , Thus, knowing the diameter of the grinding media (D) and the speed of the sand mill (RMP), the linear velocity of the grinding media can be calculated.

[0063] The media filling rate affects the grinding efficiency and product fineness. The filling rate of the horizontal sand mill is generally 80-85%. Too high a filling rate may cause excessive temperature rise or outlet blockage, while too low a filling rate will lead to low grinding efficiency and increased wear.

[0064] Specifically, in this embodiment, a temperature sensor is used to detect the temperature of the material. When the temperature of the material exceeds the set threshold, water is injected into the interlayer of the coarse grinding sand mill and the linear speed of the coarse grinding sand mill is reduced during coarse grinding. During fine grinding, water is injected into the interlayer of the fine grinding sand mill and the linear speed of the fine grinding sand mill is reduced. For example: when the sand mill is running at a speed of 15M / s, the material temperature of the entire system will continue to rise to 65 degrees. The continuous temperature increase will have a serious impact on the quality of the material. At this time, cooling water is injected into the interlayer of the sand mill to cool the temperature of the material. In addition, the system is equipped with a temperature sensor. When the material is detected to be lower than 50°C, the linear speed of the sand mill is 15M / S. When the temperature rises to 65°C, the sand mill automatically drops to 12M / S to reduce the temperature without affecting the efficiency.

[0065] In order to solve the problem of over-grinding, the optimal grinding time required was determined through experiments to accurately control the grinding time.

[0066] Through experiments, it was found that at a linear speed of 15 m / s, the finished product standard was reached in 360 minutes. Excessive grinding will make the particle size too small, resulting in a decrease in the tap density of the material, which will affect the volume energy density of the battery. Over-grinded materials may cause performance degradation during the battery charging and discharging process, such as reducing the discharge platform voltage and capacity of the battery. In this embodiment, during fine grinding, the fine grinding sand mill continues to grind for 60 minutes and then samples are taken to detect the particle size. If it does not meet the standard, continue grinding, and the particle size of the material meets the standard after about 360 minutes of continuous grinding.

[0067] This embodiment also designs a self-regulating control system. The self-regulating control system monitors key parameters in the grinding process in real time, such as temperature, mill power, material flow, product particle size, etc. The fuzzy logic controller is used to handle uncertainty and fuzziness, and the filling amount of the grinding medium, grinding speed, material flow, etc. are automatically adjusted according to the monitored parameter changes. The system can adaptively adjust the control parameters according to real-time data to cope with frequent changes in materials or other external disturbances. Such as ensuring the consistency of product particle size distribution, increasing output, reducing energy consumption or reducing circulation load. Through the closed-loop feedback mechanism, the system can continue to learn and adjust to adapt to changes in production conditions and achieve more refined control. The self-regulating control system has a user-friendly interface that allows operators to easily set up and monitor the grinding process. By precisely controlling the grinding conditions, the grinding efficiency can be improved, the risk of over-grinding can be reduced, and the consistency of product quality can be ensured. By optimizing the grinding parameters, unnecessary energy consumption can be reduced and a more environmentally friendly production process can be achieved.

[0068] Based on the sand grinding process of the lithium iron phosphate production line, the present invention also provides a control system for the lithium iron phosphate production line, including: An injection unit, the injection unit is used to inject the material to be ground into a first storage tank selected from the two first storage tanks and to inject the material in the first storage tank into the second storage tank; A coarse grinding unit, the coarse grinding unit is used to input the material in the selected first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material ground by the coarse grinding sand mill into another first storage tank. When all the materials in the selected first storage tank are emptied, the material in the other first storage tank is input into the coarse grinding sand mill for coarse grinding, and inject the material ground by the coarse grinding sand mill into the selected first storage tank. When all the materials in the other first storage tank are emptied, the current round of coarse grinding is completed and the next round of coarse grinding is carried out until a preset coarse grinding termination condition is reached; A fine grinding unit is used to input the material in the selected second storage tank into a fine grinding sand mill for fine grinding. The material ground by the fine grinding sand mill flows back to the selected second storage tank. When it is determined that the particle size of the material in the selected second storage tank meets the preset particle size requirement, the material in the selected second storage tank is output and another second storage tank is selected to start the next round of fine grinding.

[0069] Based on the above-mentioned sand grinding process of the lithium iron phosphate production line, the present invention also provides a control terminal for the lithium iron phosphate production line, the control terminal comprising a memory, a processor, and a control program for the lithium iron phosphate production line stored in the memory and executable on the processor, the control program for the lithium iron phosphate production line implementing any one of the above-mentioned steps of the sand grinding process of the lithium iron phosphate production line when executed by the processor.

[0070] It should be noted that the above embodiments are not specifically independent embodiments, and the embodiments can be combined with each other to form different implementation methods.

[0071] The above embodiments are not exhaustive enumerations of the present invention, and there may be multiple other implementations not listed. Any replacement and improvement made without violating the concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A sand grinding device for a lithium iron phosphate production line, characterized in that: include: Two first storage tanks and at least two second storage tanks, the first storage tanks are used to inject materials to be ground, and the second storage tanks are used to inject coarsely ground materials, and the first storage tanks and the second storage tanks are both provided with stirring devices; A coarse grinding sand mill and a plurality of fine grinding sand mills, wherein the coarse grinding sand mill and the fine grinding sand mill are both provided with an input end and an output end; A first switching device, the first switching device is used to connect the input end of the coarse grinding sand mill to one of the first material storage tanks and the output end to another of the first material storage tanks, and the two switching devices are interoperable; The second switching device is used to connect the input end and the output end of all the fine grinding sand mills to the second storage tank selected from all the second storage tanks.

2. The sand grinding device for the lithium iron phosphate production line according to claim 1, characterized in that: The first material storage tank is provided with a first discharge port, a first feed port and a second feed port, and the first feed port is used to inject the material to be ground; the second material storage tank is provided with a third feed port, a fourth feed port and a second discharge port, and the third feed port is used to inject the coarsely ground material; The input end of the coarse grinding sand mill is connected to the first discharge port of the first storage tank, and the output end is connected to the second feed port of the first storage tank; The input end and the output end of the fine grinding sand mill are respectively connected to the second discharge port and the fourth feed port of the second storage tank.

3. The sand grinding device for the lithium iron phosphate production line according to claim 2, characterized in that: A first discharge valve is provided on the pipeline connected to the first discharge port, a first feed valve is provided on the pipeline connected to the second feed port, and all the first discharge valves and all the first feed valves form the first switching device; A second discharge valve is provided on the pipeline connected to the second discharge port, and a second feed valve is provided on the pipeline connected to the fourth feed port. All the second discharge valves and all the second feed valves form the second switching device.

4. The sand grinding device for the lithium iron phosphate production line according to claim 1, characterized in that: The grinding medium of the coarse grinding sand mill is zirconium beads with a particle size of 0.8 mm, and the grinding medium of the fine grinding sand mill is zirconium beads with a particle size of 100 um.

5. The sand grinding device for the lithium iron phosphate production line according to claim 1, characterized in that: A sampling hand valve for sampling and testing is arranged on the pipeline connected to the second discharge port.

6. A lithium iron phosphate production line device, characterized in that: include: A premixing device, a sand grinding device as described in any one of claims 1 to 5, an iron removal device and a finished product device connected in sequence.

7. A sand grinding process for a lithium iron phosphate production line, characterized in that: include: injecting the material to be ground into the selected first storage tank; Input the material in the selected first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material after the coarse grinding sand mill into another first storage tank. When all the materials in the selected first storage tank are emptied, input the material in the other first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material after the coarse grinding sand mill into the selected first storage tank. When all the materials in the other first storage tank are emptied, the current round of coarse grinding is completed and the next round of coarse grinding is carried out until the preset coarse grinding termination condition is reached; Injecting the material in the first storage tank into the selected second storage tank; The material in the selected second storage tank is input into the fine grinding sand mill for fine grinding, and the material ground by the fine grinding sand mill flows back to the selected second storage tank. When it is determined that the particle size of the material in the selected second storage tank meets the preset particle size requirement, the material in the selected second storage tank is output and another second storage tank is selected to start the next round of fine grinding.

8. The sand grinding process of the lithium iron phosphate production line according to claim 7, characterized in that: Determining whether the particle size of the material in the selected second storage tank meets the preset particle size requirement includes: Using a laser particle size analyzer to analyze the particle size of the material in the selected second storage tank to obtain particle size distribution data; Determine whether the particle size distribution data meets the preset particle size requirements.

9. The sand grinding process of the lithium iron phosphate production line according to claim 7, characterized in that: The material is coarsely ground in the coarse grinding sand mill using zirconium beads with a particle size of 0.8 mm, and the material is finely ground in the fine grinding sand mill using zirconium beads with a particle size of 100 um.

10. The sand grinding process of the lithium iron phosphate production line according to claim 7, characterized in that: Also includes: Use sensors to obtain grinding parameters in real time; According to the grinding parameters, at least one of the filling amount of the grinding medium, the grinding linear speed, and the material flow rate is adjusted.

11. The sand grinding process of the lithium iron phosphate production line according to claim 10, characterized in that: The sensor comprises a temperature sensor, and when it is detected that the temperature of the material exceeds a set threshold, water is injected into the interlayer of the coarse grinding sand mill and / or the fine grinding sand mill and the linear speed of the coarse grinding sand mill and / or the fine grinding sand mill is reduced.

12. A control system for a lithium iron phosphate production line, characterized in that: include: An injection unit, the injection unit is used to inject the material to be ground into a first storage tank selected from the two first storage tanks and to inject the material in the first storage tank into the second storage tank; A coarse grinding unit, the coarse grinding unit is used to input the material in the selected first storage tank into the coarse grinding sand mill for coarse grinding, and inject the material ground by the coarse grinding sand mill into another first storage tank. When all the materials in the selected first storage tank are emptied, the material in the other first storage tank is input into the coarse grinding sand mill for coarse grinding, and inject the material ground by the coarse grinding sand mill into the selected first storage tank. When all the materials in the other first storage tank are emptied, the current round of coarse grinding is completed and the next round of coarse grinding is carried out until a preset coarse grinding termination condition is reached; A fine grinding unit is used to input the material in the selected second storage tank into a fine grinding sand mill for fine grinding. The material ground by the fine grinding sand mill flows back to the selected second storage tank. When it is determined that the particle size of the material in the selected second storage tank meets the preset particle size requirement, the material in the selected second storage tank is output and another second storage tank is selected to start the next round of fine grinding.

13. A control terminal for a lithium iron phosphate production line, characterized in that: The control terminal includes a memory, a processor, and a control program for the lithium iron phosphate production line stored in the memory and executable on the processor. When the control program for the lithium iron phosphate production line is executed by the processor, the steps of the sanding process of the lithium iron phosphate production line as described in any one of claims 7 to 11 are implemented.

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