Separation device and separation method for magnetic foreign matters in silicon-based negative electrode powder of lithium battery

Abstract

The application provides a lithium battery silicon-based negative electrode powder magnetic foreign matter separation device and separation method, the separation device comprises a fixed seat, a separation processing unit rotatably arranged on the fixed seat, and an ultrasonic unit; the separation processing unit comprises a first processing container with a processing chamber and a second processing container with a buffer chamber, the first processing container and the second processing container are connected, and the material in the buffer chamber can be unidirectionally transported into the processing chamber; the ultrasonic unit comprises an ultrasonic medium tank with a liquid outlet, the first processing container can be rotated into the ultrasonic medium tank, and the discharge port can selectively communicate with the ultrasonic medium tank. The lithium battery silicon-based negative electrode powder magnetic foreign matter separation device can improve the dispersion degree of the silicon-based negative electrode powder and the exposure degree of the magnetic foreign matter through the rotating separation processing unit and the ultrasonic unit, thereby improving the effective adsorption rate of the magnetic foreign matter, and making the test result more close to the true value.

Description

Technical Field

[0001] This invention relates to the field of battery material testing technology, and in particular to a device for separating magnetic foreign matter from silicon-based anode powder for lithium batteries. This invention also relates to a method for separating magnetic foreign matter from silicon-based anode powder for lithium batteries. Background Technology

[0002] With the diversification of lithium battery material systems, the evaluation indicators and testing methods for electrode materials, electrolytes, and separators remain incomplete. Among electrode materials, silicon-based anode materials, as a promising next-generation lithium battery anode material, possess advantages such as high energy density, wide raw material distribution, and a suitable discharge platform. Since magnetic foreign matter in electrode materials can affect battery thermal stability and consistency, leading to reduced battery safety performance, lithium battery companies urgently need to establish a comprehensive testing system for magnetic foreign matter in electrode materials.

[0003] Because silicon-based anode powders are oleophilic and hydrophobic, prone to agglomeration, and have low density, existing technologies typically employ conventional dispersion systems such as pure water, ethanol, and NMP (N-methylpyrrolidone) to expose magnetic foreign matter and facilitate adsorption by magnetic rods in order to separate magnetic foreign matter from the silicon-based anode powder and achieve testing objectives. However, current dispersion systems are difficult to achieve effective dispersion; interparticle forces are mainly attractive, resulting in significant agglomeration. Some magnetic foreign matter is not fully exposed, leading to low effective adsorption rates in the magnetic separation process, and the testing process generates a large amount of costly suspended solids waste liquid. Summary of the Invention

[0004] In view of this, the present invention aims to provide a device for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries, so as to improve the adsorption rate of magnetic foreign matter.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A device for separating magnetic foreign matter in lithium battery silicon-based negative electrode powder, the device comprising a fixed base, a separation processing unit rotatably mounted on the fixed base, and an ultrasonic unit located below the separation processing unit;

[0007] The separation and processing unit includes a first processing container with a processing chamber and a second processing container with a buffer chamber. The first processing container and the second processing container are connected, and the material in the buffer chamber can be unidirectionally conveyed to the processing chamber.

[0008] The first processing container is provided with a first inlet and a first outlet communicating with the processing chamber, and the second processing container is provided with a dispersant inlet and a cleaning agent inlet communicating with the buffer chamber.

[0009] The ultrasonic unit includes an ultrasonic medium tank with a drain outlet, the first processing container is rotatable into the ultrasonic medium tank, and the first discharge port is selectively connected to the ultrasonic medium tank.

[0010] Furthermore, a connecting pipeline is provided between the processing chamber and the buffer chamber, and a first unidirectional guide is provided on the connecting pipeline.

[0011] Furthermore, a second one-way guide is provided at the first discharge port. When the first processing container rotates into the ultrasonic medium tank, the processing chamber is connected to the ultrasonic medium tank through the second one-way guide.

[0012] Furthermore, the ultrasonic medium tank is equipped with a detection device for detecting the temperature and level of the liquid inside the tank.

[0013] Furthermore, the fixed base is provided with an aeration device, which has a plurality of aeration ports located in the ultrasonic medium tank.

[0014] Furthermore, the fixed base is provided with a cooling water channel for injecting coolant into the ultrasonic medium tank, and / or the fixed base is provided with a dispersant pipeline connected to the dispersant inlet and a cleaning agent pipeline connected to the cleaning agent inlet.

[0015] Furthermore, the fixed base is provided with a driving device to drive the separation unit to rotate, and / or, the separation processing unit is a plurality of units arranged circumferentially along the rotation center.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The magnetic foreign matter separation device for lithium battery silicon-based anode powder of the present invention, through the setting of a processing unit and an ultrasonic unit, allows the separation process of silicon-based anode powder and magnetic foreign matter to be carried out in the processing chamber. A dispersant is delivered to the processing chamber through a buffer chamber to wet the silicon-based anode powder. Under the friction and shearing action provided by the rotation of the separation unit and the cavitation effect of the ultrasonic unit, the dispersion degree of silicon-based anode powder can be improved, allowing the magnetic foreign matter to be better exposed. This can improve the effective adsorption rate of magnetic foreign matter, making the test results closer to the true value.

[0018] Furthermore, the connecting pipeline and the first unidirectional guide component on the connecting pipeline are characterized by their simple structure and ease of design and implementation, and also facilitate the unidirectional transport of materials from the buffer chamber to the processing chamber. The second unidirectional guide component facilitates the transport of materials from the processing chamber to the ultrasonic medium tank. The detection device is useful for detecting the temperature and level of the liquid in the ultrasonic medium tank.

[0019] Secondly, the aeration device effectively prevents the sedimentation of silicon-based anode powder in the treatment solution during cleaning, thus facilitating its cleaning and recovery. The cooling water circuit allows for the injection of cooling water into the ultrasonic medium tank, lowering the equipment temperature to prevent overheating, which could affect the magnetic flux of the magnetic rods, reduce adsorption efficiency, and extend the equipment's service life. The cleaning agent pipeline facilitates the cleaning function of the separation device.

[0020] In addition, the drive device is designed to enable the intermittent reciprocating rotation of the separation processing unit. The separation processing unit is configured as multiple units arranged circumferentially along the rotation center, which helps to improve the separation efficiency of silicon-based anode powder.

[0021] Another objective of this invention is to provide a method for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries, the separation method comprising the following steps:

[0022] Step s1: Clean the separation device and observe its cleanliness. If there are obvious solid impurities attached, repeat the cleaning until the cleanliness of the separation device meets the standard.

[0023] Step s2: Filling materials: A certain amount of silicon-based negative electrode powder and several magnetic rods are loaded into the processing chamber, and the sealing of the processing chamber is ensured.

[0024] Step s3: Pre-disperse the silicon-based anode material from step s2, start the ultrasonic unit, rotate the processing chamber into the ultrasonic medium tank, add a certain proportion of organic dispersant into the buffer chamber through the dispersant inlet, and connect the buffer chamber and the processing chamber to allow the organic dispersant to be input into the processing chamber to wet the silicon-based anode powder.

[0025] Step s4: Separate the pre-dispersed silicon-based anode powder from step s3. The processing chamber rotates back and forth, causing the material in the processing chamber to be in an intermittent tumbling motion. The original agglomerates of the silicon-based anode powder are deagglomerated and dispersed under the combined action of wetting by the organic dispersant, ultrasonic assisted cavitation, and friction and shearing generated by the rolling of the magnetic rod, so that the magnetic foreign matter is completely exposed and adsorbed on the surface of the magnetic rod.

[0026] Step s5: The treatment liquid containing silicon-based negative electrode powder after separation in step s4 is input into the ultrasonic medium tank through the first discharge port and discharged out of the ultrasonic medium tank through the drain port. Then, the cleaning agent is input into the buffer chamber through the cleaning agent inlet to clean the organic dispersant remaining on the magnetic rod. After cleaning, the treatment chamber and the ultrasonic medium tank are connected, and then the waste liquid after cleaning is discharged out of the ultrasonic medium tank through the drain port.

[0027] Step s6: Take out the cleaned magnetic rod from step s5 and transfer it to a digestion tube. Digest it with 50% aqua regia at 100°C for 60 minutes. Then dilute the resulting solution and perform quantitative analysis on the content of magnetic foreign matter.

[0028] Furthermore, in step s5, during the process of the treatment liquid being input into the ultrasonic medium tank and discharged through the drain port, an aeration device is used to aerate the treatment liquid; and / or, the separation method further includes: step 7: cleaning the used treatment chamber and buffer chamber until the cleaning is qualified, and then discharging the cleaned waste liquid out of the ultrasonic medium tank through the drain port.

[0029] Furthermore, in step s3, the organic dispersant is a solution prepared from triethanolamine and water, with a volume ratio of triethanolamine to water of 1:3; and / or, the mass ratio of silicon-based anode powder to organic dispersant is between 20% and 200%.

[0030] The present invention discloses a method for separating magnetic foreign matter from silicon-based anode powder in lithium batteries. By wetting the silicon-based anode powder with an organic dispersant and subjecting it to intermittent tumbling motion in a processing chamber, and by applying ultrasonic cavitation, the original agglomerates of the silicon-based anode powder can be better deagglomerated and dispersed, so that the magnetic foreign matter is fully exposed and adsorbed on the surface of the magnetic rod, thereby improving the effective adsorption rate of the magnetic foreign matter.

[0031] In addition, the intermittent reciprocating rotation of the processing chamber and buffer chamber allows the material to move intermittently in a tilting motion within the processing chamber. The broken peripheral particles can be quickly transferred and mixed with the organic dispersant. This prevents the particles from re-agglomerating and fully exposes the internal agglomerates, achieving deagglomeration and dispersion. This improves the exposure of magnetic foreign matter and the effective adsorption rate of magnetic foreign matter, thus making the test structure closer to the true value.

[0032] In addition, aeration devices can be used to aerate the treatment liquid, which can effectively stir the liquid and prevent the silicon-based anode powder from settling and accumulating, thus facilitating the cleaning and recycling of the silicon-based anode powder.

[0033] In addition, the organic dispersant is made of triethanolamine and water, and the volume ratio of triethanolamine to water is 1:3. This not only ensures the wetting effect of silicon-based anode powder, but also avoids the problem that triethanolamine has high viscosity at room temperature and is not easy to transport, thus ensuring the smooth input of the organic dispersant. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is a front view of the magnetic foreign matter separation device for lithium battery silicon-based negative electrode powder according to an embodiment of the present invention;

[0036] Figure 2 This is a top view of the magnetic foreign matter separation device for lithium battery silicon-based negative electrode powder according to an embodiment of the present invention;

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Fixed base; 2. Drive device; 3. First treatment container; 4. Second treatment container; 5. Ultrasonic media tank; 6. Sedimentation tank; 7. Discharge pipe; 8. Aeration pipe;

[0039] 201, Drive shaft; 300, Processing chamber; 301, First inlet; 302, First outlet; 3011, Cover; 3012, Leak-proof gasket; 3013, Threaded opening; 400, Buffer chamber; 401, Dispersant inlet; 402, Cleaning agent inlet; 501, Drain outlet;

[0040] 13. Cleaning agent storage tank; 14. Pure water storage tank; 15. Dispersant storage tank; 17. Central control panel; 18. Detection device; 19. Transducer vibrator; 22. Aeration port; 23. Dispersant pipeline; 24. Cleaning agent pipeline; 25. Cooling water pipeline;

[0041] 10. First unidirectional guide component; 20. Second unidirectional guide component; 30. Automatic shut-off valve; 40. Automatic gate valve. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0043] In the description of this invention, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer," indicating orientation or positional relationship, is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first" and "second" is also for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0045] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] This embodiment relates to a device for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries, which can improve the effective adsorption rate of magnetic foreign matter and make the test structure closer to the true value.

[0047] In terms of overall structure, the separation device for magnetic foreign matter in the lithium battery silicon-based anode powder of this embodiment is as follows: Figure 1 and Figure 2 As shown, the separation device mainly includes a fixed base 1, a separation processing unit rotatably mounted on the fixed base 1, and an ultrasonic unit located below the separation processing unit.

[0048] The separation unit is capable of intermittent rotation relative to the fixed base 1, and includes a first processing container 3 and a second processing container 4 connected together. The first processing container 3 has a processing chamber 300, and the second processing container 4 has a buffer chamber 400. Moreover, the processing chamber 300 and the buffer chamber 400 are unidirectionally connected, that is, the material in the buffer chamber 400 can be unidirectionally transported to the processing chamber 300.

[0049] See Figure 1 and Figure 2 As shown, in this embodiment, the first processing container 3 is provided with a first inlet 301 and a first outlet 302 for the powder to be separated, and the second processing container 4 is provided with a dispersant inlet 401 and a cleaning agent inlet 402. The first inlet 301 is used to feed silicon-based anode powder and magnetic rods into the processing chamber 300. Specifically, the diameter of the first inlet 301 is larger than the diameter of the first outlet 302, as shown... Figure 1 As shown, the first feed port 301 has a threaded opening 3013 formed on the first processing container 3, and a cover 3011 screwed onto the threaded opening 3013. A leak-proof gasket 3012 is provided between the cover 3011 and the threaded opening 3013 so that the sealing effect of the processing chamber 300 can be guaranteed when the cover 3011 is screwed onto the threaded opening 3013.

[0050] In this embodiment, the ultrasonic unit includes an ultrasonic medium tank 5 with a drain port 501. The first processing container 3 can be intermittently rotated into the ultrasonic medium tank 5, and the first discharge port 302 can selectively communicate with the ultrasonic medium tank 5. Thus, the separated processing liquid containing silicon-based negative electrode powder can be input into the ultrasonic medium tank 5 and discharged from the ultrasonic medium tank 5 through the drain port 501, which also facilitates the cleaning of the buffer chamber 400 and the processing chamber 300. Furthermore, the transducer array 19 at the bottom of the ultrasonic medium tank 5 can realize the conversion between electrical energy and acoustic energy.

[0051] In a preferred embodiment, a connecting pipeline is provided between the processing chamber 300 and the buffer chamber 400, and a first unidirectional guide 10 is provided on the connecting pipeline. This facilitates the unidirectional transport of materials in the buffer chamber 400 to the processing chamber 300, and has the characteristics of simple structure and easy design and implementation.

[0052] Similarly, as a preferred embodiment, in this embodiment, a second one-way guide 20 is provided at the first discharge port 302. When the first processing container 3 rotates into the ultrasonic medium tank 5, the processing chamber 300 is connected to the ultrasonic medium tank 5 through the second one-way guide 20, which facilitates the conveying of materials in the processing chamber 300 to the ultrasonic medium tank 5.

[0053] It should be noted that the first unidirectional guide 10 and the second unidirectional guide 20 mentioned above can preferably be one-way valves, which have the characteristics of wide applicability and ease of operation.

[0054] To facilitate the detection of the temperature and level of the liquid in the ultrasonic medium tank 5, in this embodiment, a detection device 18 for detecting the temperature and level of the liquid in the ultrasonic medium tank 5 is provided. This detection device 18 can be a sensor integrating temperature and pressure detection, or a temperature sensor for temperature detection or a pressure transmitter for pressure detection, etc., to facilitate automated control.

[0055] In this embodiment, preferably, an aeration device is also provided on the fixed base 1. The aeration device has several aeration ports 22 located inside the ultrasonic medium tank 5. Specifically, the aeration device includes an aeration pipe 8 and an air compressor. One end of the aeration pipe 8 is connected to the air compressor, and the other end forms multiple aeration ports 22. The end with the aeration ports 22 is located inside the ultrasonic medium tank 5, so that aeration can be introduced into the ultrasonic medium tank 5 through the aeration ports 22. In this way, when cleaning the treatment liquid, the sedimentation of silicon-based anode powder in the treatment liquid can be effectively prevented, and the cleaning and recycling of silicon-based anode powder can also be facilitated. Furthermore, to facilitate the start and stop of the aeration operation, an automatic gate valve 40 is provided on the aeration pipe 8 in this embodiment to facilitate the automatic start of the aeration operation.

[0056] Since the ultrasonic unit has a certain thermal effect, the temperature of the separation device will rise after working for a certain period of time. In order to prevent the magnetic flux and adsorption efficiency of the magnetic rod from being affected by the excessively high temperature of the equipment, in this embodiment, a cooling water pipe 25 for injecting coolant into the ultrasonic medium tank 5 is provided on the fixed base 1. In this way, cooling water can be injected into the ultrasonic medium tank 5 through the cooling water pipe 25 to reduce the temperature of the equipment and ensure the working life of the device.

[0057] In practice, when the temperature of the liquid in the tank is detected to be higher than the preset temperature, cooling water can be injected into the ultrasonic medium tank 5 through the cooling water pipe 25. Once the detected temperature reaches the preset range, the injection of cooling water into the ultrasonic medium tank 5 is stopped. It should be noted that the preset temperature range in this embodiment is preferably set between 30℃ and 40℃.

[0058] Furthermore, as a preferred embodiment of this invention, the fixed base 1 is provided with a dispersant pipeline 23 communicating with the dispersant inlet 401 and a cleaning agent pipeline 24 communicating with the cleaning agent inlet 402. The end of the dispersant pipeline 23 furthest from the dispersant inlet 402 is connected to the dispersant storage tank 15. The end of the cleaning agent pipeline 24 furthest from the cleaning agent inlet 402 is connected to the cleaning agent storage tank 13. This facilitates the cleaning function of the separation device and the maintenance of the separation device.

[0059] It is worth noting that, in this embodiment, the dispersant is preferably an organic dispersant prepared from triethanolamine and pure water, wherein the volume ratio of triethanolamine to water is 1:3, to achieve a better wetting effect on the silicon-based anode powder. The cleaning agent in this embodiment is preferably ethanol or pure water. It is also worth noting that the portion of the dispersant pipeline 23 connected to the dispersant inlet 401, and the portion of the cleaning agent pipeline 24 connected to the cleaning agent inlet 402, are preferably made of flexible tubing to ensure smooth reciprocating rotation of the separation unit.

[0060] In a preferred embodiment of this invention, a drive device 2 for rotating the separation unit is provided on the fixed base 1 to facilitate the intermittent reciprocating motion of the separation unit. Preferably, the drive device 2 in this embodiment is a motor, and the separation unit is connected to the drive shaft 201 of the motor 2, so that the separation unit can rotate relative to the fixed base 1 under the drive of the motor 2.

[0061] Similarly, as a preferred embodiment of this invention, in this embodiment, the separation processing unit comprises multiple units arranged circumferentially along the rotation center. For example... Figure 1As shown, there are four separation processing units arranged circumferentially along the rotation center. The processing chamber 300 and buffer chamber 400 in each separation processing unit are arranged radially, and the buffer chamber 400 is arranged near the rotation center.

[0062] In addition, to facilitate the collection of the treated liquid, in this embodiment, a discharge pipe 7 is provided at the discharge port 501 of the ultrasonic medium tank 5, and the other end of the discharge pipe 7 is connected to the sedimentation tank 6. Thus, the treated liquid discharged through the discharge port 501 can be collected into the sedimentation tank 6 through the discharge pipe 7 for subsequent purification treatment. To facilitate the control of the discharge of the treated liquid, an automatic shut-off valve 30 is provided on the discharge pipe 7.

[0063] To facilitate automated operation of the separation device, a central control console 17 is also provided on the fixed base 1 in this embodiment. The signal lines of the motor 2 and the detection device 18 are all connected to the central control console 17. The control program of the central control console 17 can be designed according to actual needs and in combination with existing mature programming technologies.

[0064] The separation device for magnetic foreign matter in lithium battery silicon-based anode powder of this embodiment, through the setting of a processing unit and an ultrasonic unit, enables the silicon-based anode powder and magnetic rod to be separated in the processing chamber 300. A dispersant is delivered to the processing chamber 300 through a buffer chamber 400 to wet the silicon-based anode powder. The friction and shearing action provided by the rotation of the separation unit, as well as the cavitation effect of the ultrasonic unit, improve the dispersion of the silicon-based anode powder, allowing the magnetic foreign matter to be better exposed. This increases the effective adsorption rate of the magnetic foreign matter, making the test results closer to the true value. Furthermore, the separation device of this embodiment only requires manual loading of materials and removal of the magnetic rod, significantly reducing repetitive manual operations and effectively lowering labor costs.

[0065] Furthermore, this embodiment also relates to a method for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries. Specifically, this separation method includes the following steps:

[0066] Step s1: Clean the separation device and observe its cleanliness. If there are obvious solid impurities attached, repeat the cleaning until the cleanliness of the separation device meets the standard.

[0067] Step s2: Filling materials: A certain amount of silicon-based negative electrode powder and several magnetic rods are loaded into the processing chamber 300, and the sealing of the processing chamber 300 is ensured.

[0068] Step s3: Pre-disperse the silicon-based anode material from step s2, start the ultrasonic unit, rotate the processing chamber 300 into the ultrasonic medium tank 5, add a certain proportion of organic dispersant into the buffer chamber 400 through the dispersant inlet 401, and connect the buffer chamber 400 and the processing chamber 300 so that the organic dispersant is input into the processing chamber 300 to wet the silicon-based anode powder;

[0069] Step s4: Separate the pre-dispersed silicon-based anode powder from step s3. The processing chamber 300 is rotated back and forth, so that the material in the processing chamber 300 is in an intermittent tumbling motion. The original agglomerates of the silicon-based anode powder are deagglomerated and dispersed under the combined action of wetting by the organic dispersant, ultrasonic assisted cavitation, and friction and shearing generated by the rolling of the magnetic rod, so that the magnetic foreign matter is completely exposed and adsorbed on the surface of the magnetic rod.

[0070] Step s5: The treatment liquid containing silicon-based negative electrode powder after separation in step s4 is input into the ultrasonic medium tank 5 through the first discharge port 302 and discharged out of the ultrasonic medium tank 5 through the drain port 501. Then, the cleaning agent is input into the buffer chamber 400 through the cleaning agent inlet 402 to clean the organic dispersant remaining on the magnetic rod. After cleaning, the treatment chamber 300 and the ultrasonic medium tank 5 are connected. Then, the waste liquid after cleaning is discharged out of the ultrasonic medium tank 5 through the drain port 502.

[0071] Step s6: Take out the cleaned magnetic rod from step s5 and transfer it to a digestion tube. Digest it with 50% aqua regia at 100°C for 60 minutes. Then dilute the resulting solution and perform quantitative analysis on the content of magnetic foreign matter.

[0072] In a preferred embodiment, the separation method further includes: Step 7: Cleaning the used processing chamber 300 and buffer chamber 400 until the cleaning is qualified, and then discharging the waste liquid after cleaning out of the ultrasonic medium tank through the drain port 501.

[0073] Preferably, in step s5, during the process of the treatment liquid being input into the ultrasonic medium tank 5 and discharged through the drain port 501, an aeration device is used to aerate the treatment liquid. This can achieve a better stirring effect on the treatment liquid, so as to avoid the sedimentation and accumulation of silicon-based anode powder and facilitate the cleaning and recycling of silicon-based anode powder.

[0074] Also preferably, in this embodiment, the organic dispersant in step s3 is a solution prepared from triethanolamine and water, with a volume ratio of triethanolamine to water of 1:3. Furthermore, the mass ratio of silicon-based anode powder to organic dispersant is between 20% and 200%, preferably 30%. This mass ratio not only ensures the wettability of the silicon-based anode powder but also has a lower cost, while also saving on the high cost of treating suspended solids wastewater later.

[0075] The separation method of this embodiment will be described in detail below with specific examples.

[0076] The separation method in this embodiment mainly includes the following steps: cleaning the separation device before use, filling materials, pre-dispersion treatment, separation treatment, cooling of the device, cleaning process (including discharge of the treatment liquid and cleaning and removal of the magnetic rod), and cleaning of the separation device after use.

[0077] The separation method in this embodiment is implemented based on the above-described separation device. One working cycle T consists of two clockwise and two counterclockwise rotations of the separation unit, totaling 496 seconds. Using one-way valve A1 as a reference, the separation unit pauses for 60 seconds at 0°, 90°, 180°, and 270° during the first counterclockwise rotation and the second clockwise rotation, repeating this pause eight times for a total of 480 seconds. The non-dwelling time is within the device's rotation speed of 15 r / min. Details of the working cycle are shown in the table below:

[0078]

[0079] Cleaning of the separation device before use:

[0080] The central control panel 17 initiates the cleaning process, with all one-way valves, detection devices 18, and automatic gate valves 40 in the closed state, and automatic shut-off valves 30 in the open state.

[0081] The cleaning process consists of three module work cycles T. Using one-way valve A1 as a reference, when the separation unit stops at 0°, 90°, 180°, and 270° during the first counter-clockwise rotation, the central control panel 17 opens the cleaning agent pipeline 24, outputting 50ml of ethanol to the buffer chamber 400. The first one-way guide 10 in the separation unit, located in the ultrasonic medium tank 5, opens, allowing ethanol to be accurately input into the corresponding processing chamber 300, wetting any remaining material in the processing chamber 300. After the stop, the corresponding first one-way guide 10 is closed.

[0082] When the separation unit stops at 0°, 90°, 180° and 270° in the second clockwise rotation, 200ml of pure water is output from the cleaning agent pipeline 24 to the buffer chamber 400. The first one-way guide 10 and the second one-way guide 20 in the separation unit in the ultrasonic medium tank 5 are opened at the same time, and the pure water is accurately input into the corresponding processing chamber 300. The material attached to the pipeline is cleaned by the strong shear force of turbulence. The cleaning waste liquid is output into the ultrasonic medium tank 5 through the corresponding second one-way guide 20, and then flows into the sedimentation tank 6 through the opening of the automatic shut-off valve 30. After the stop is completed, the corresponding first one-way guide 10 and the second one-way guide 20 are closed at the same time. That is, one-way valves A1 and B1 are a group, one-way valves A2 and B2 are a group, one-way valves A3 and B3 are a group, and one-way valves A4 and B4 are a group. The one-way valves of each group are closed at the same time. Then, observe the cleanliness of the system. If there are obvious solid impurities attached, repeat the cleaning process on the center console 17 several times until the system cleanliness meets the standard.

[0083] Filling materials:

[0084] The pre-weighed silicon-based anode powder (200±2g) and a magnetic rod (magnetic flux of 6000±100, size Φ17mm×52mm, the outer surface of the magnetic rod is wrapped with polytetrafluoroethylene) are filled into the corresponding processing chamber 300, and the processing chamber 300 is sealed by a leak-proof gasket 3012. The magnetic flux of the magnetic rod is 6000±100 to prevent the test results from deviating from the true value due to either too low a magnetic flux (low effective adsorption rate of magnetic foreign matter) or too high a magnetic flux (magnetization of the material).

[0085] Pre-dispersion treatment: The central control unit 17 initiates the pre-dispersion process. Automatic gate valve 40 and automatic shut-off valve 30 are closed, while the detection device 18 is open. The central control unit 17 opens the cooling water pipe 25, introducing cooling water as the ultrasonic medium into the ultrasonic medium tank 5. Through detection by the detection device 18, the liquid level in the ultrasonic medium tank 5 reaches the preset value, and the central control unit 17 closes the cooling water pipe 25. Next, the central control unit 17 activates ultrasonic assistance by controlling the transducer vibrator 19.

[0086] The pre-dispersion process consists of one working cycle T. Using the one-way check valve A1 as a reference, when the separation unit stops at 0°, 90°, 180°, and 270° during the first counter-clockwise rotation, the central control panel 17 opens the dispersant pipeline 23, outputting a certain proportion of organic dispersant to the buffer chamber 400. In the separation unit located in the ultrasonic medium tank 5, the one-way valve in this separation unit opens, and the organic dispersant is accurately input into the corresponding processing chamber 300. After the stop, the corresponding one-way valve closes. The separation unit stops again at 0°, 90°, 180°, and 270° during the second clockwise rotation. After this stop, the process proceeds to the next stage.

[0087] In the pre-dispersion process, the organic dispersant is prepared by mixing triethanolamine and water in a volume ratio of 1:3. This pre-prepared organic dispersant can avoid the problem of difficult transportation caused by the high viscosity of triethanolamine at room temperature, and also facilitates the separation device to accurately control the input amount of the dispersant.

[0088] Separation process: After the pre-dispersion process is completed, the central control panel 17 starts the processing process, and the automatic gate valve 40, automatic shut-off valve 30 and each check valve are in the closed state.

[0089] The processing procedure consists of 10 working cycles (T). Under the combined action of dispersant wetting, ultrasonic-assisted cavitation, and friction and shearing generated by the rolling of the magnetic rod, the primary agglomerates of silicon-based anode powder are deagglomerated and dispersed, fully exposing the magnetic foreign matter, which can then be better adsorbed onto the surface of the magnetic rod.

[0090] Cooling of the device:

[0091] Because ultrasound has a certain thermal effect, if the equipment temperature is too high after a certain period of operation, it will reduce the magnetic flux of the magnetic rod, thereby limiting the effective adsorption rate of the magnetic rod for magnetic foreign objects, and will also affect the working life of the transducer oscillator.

[0092] When the liquid temperature in the ultrasonic medium tank 5 reaches the preset temperature TMax40℃, the central control panel 17 initiates the cooling process, with the one-way valve in the closed state. This continues until the temperature drops below the preset temperature TMin30℃, at which point the cooling water pipe 25 and the automatic shut-off valve 30 are simultaneously closed. If the liquid level falls below the preset value, the cooling water pipe 25 is opened, and the automatic shut-off valve 30 remains closed until the liquid level reaches the preset value, at which point the cooling water pipe 25 is closed.

[0093] Cleaning process: After the separation process is completed, the central control panel 17 starts the cleaning process. The central control panel 17 opens the automatic shut-off valve 30, and the fluid medium in the ultrasonic medium tank 5 is output to the sedimentation tank 6. When the liquid level in the tank is 30% of the height of the ultrasonic medium tank, the central control panel 17 turns on the aeration device to provide a stirring effect on the one hand, and the generated micro bubbles enhance the ultrasonic cavitation effect on the other hand, preventing large particles in the cleaning fluid from clogging the pipeline. The automatic gate valve 30 is in the open state.

[0094] The cleaning process consists of two working cycles T. Based on the one-way check valve A1, when the separation unit stops at 0°, 90°, 180° and 270° in the first counterclockwise cycle and the second clockwise cycle, the central control panel 17 opens the cleaning agent pipeline 24, outputting 50ml of pure water to the buffer chamber 400. In the separation unit located in the ultrasonic medium tank 5, the one-way valves A and B in the separation unit, namely the first one-way guide 10 and the second one-way guide 20, are opened simultaneously. Pure water is accurately input into the corresponding processing chamber 300. The material attached to the pipeline is cleaned by the strong shear force of turbulence. The cleaning waste liquid is output to the ultrasonic medium tank 5 through the one-way valve B, and then flows into the sedimentation tank 6 through the discharge pipe 7. After the stop is completed, the corresponding one-way valves A and B close simultaneously.

[0095] Next, the cleaned magnetic rod was removed and transferred to a digestion tube. It was then digested with 50% aqua regia for 90 minutes. The resulting solution was then diluted and quantitatively analyzed for the content of magnetic foreign matter using ICP-OES (inductively coupled plasma optical emission spectrometry).

[0096] The cleaning method for the separation device after use is the same as that for the cleaning method before use, and will not be repeated here.

[0097] The present invention provides a method for separating magnetic foreign matter from silicon-based anode powder in lithium batteries. By employing ultrasonic assistance, pre-dispersion using an organic dispersion system, and a rotating processing chamber, along with the mutual grinding action of rotating magnetic rods, the original agglomerates of silicon-based anode powder can be better deagglomerated and dispersed, allowing the magnetic foreign matter to be fully exposed and adsorbed onto the surface of the magnetic rods, thereby improving the effective adsorption rate of the magnetic foreign matter.

[0098] Furthermore, the intermittent reciprocating rotation of the processing chamber 300 and the buffer chamber 400 facilitates the intermittent tumbling motion of the material within the processing chamber 300. This allows the broken peripheral particles to be rapidly transferred and mixed with the organic dispersant, preventing the particles from re-agglomerating and fully exposing the internal agglomerates, thereby achieving deagglomeration and dispersion. This improves the exposure of magnetic foreign matter and its effective adsorption rate, resulting in a test structure that is closer to the true value.

[0099] Furthermore, in the separation method of this embodiment, under the ultrasonic-assisted cavitation and the wetting effect of the organic dispersion system, the interparticle forces of the silicon-based negative electrode powder are mainly repulsive, and the interparticle interface changes from a solid-solid interface to a solid-liquid or solid-gas interface. The powder dispersion is relatively high, and the friction and shearing action generated by the rolling and sliding of the grinding media magnetic rod can deagglomerate and disperse the original agglomerates that are mechanically overlapped and interlocked, completely exposing the magnetic foreign matter, thereby improving the effective adsorption rate of the magnetic separation process and making the test results closer to the true value.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries, characterized in that: The separation device includes a fixed base, a separation processing unit rotatably mounted on the fixed base, and an ultrasonic unit located below the separation processing unit. The separation and processing units are multiple units arranged circumferentially along the rotation center. Each separation and processing unit includes a first processing container with a processing chamber and a second processing container with a buffer chamber. The first processing container and the second processing container are connected, and the material in the buffer chamber can be unidirectionally conveyed to the processing chamber. The first processing container is provided with a first inlet and a first outlet communicating with the processing chamber. The second processing container is provided with a dispersant inlet and a cleaning agent inlet communicating with the buffer chamber. A certain proportion of organic dispersant is added to the buffer chamber through the dispersant inlet. The organic dispersant is a solution of triethanolamine and water, with a volume ratio of triethanolamine to water of 1:

3. The ultrasonic unit includes an ultrasonic medium tank with a drain outlet, the first processing container can be rotated into the ultrasonic medium tank, and the first discharge port can selectively communicate with the ultrasonic medium tank. The processing chamber rotates back and forth, and the material inside the processing chamber is in an intermittent tumbling motion.

2. The device for separating magnetic foreign matter from lithium battery silicon-based anode powder according to claim 1, characterized in that: A connecting pipeline is provided between the processing chamber and the buffer chamber, and a first one-way conduction element is provided on the connecting pipeline.

3. The device for separating magnetic foreign matter from lithium battery silicon-based negative electrode powder according to claim 1, characterized in that: A second one-way guide is provided at the first discharge port. When the first processing container rotates into the ultrasonic medium tank, the processing chamber is connected to the ultrasonic medium tank through the second one-way guide.

4. The device for separating magnetic foreign matter from lithium battery silicon-based negative electrode powder according to claim 1, characterized in that: The ultrasonic medium tank is equipped with a detection device for detecting the temperature and level of the liquid inside the tank.

5. The device for separating magnetic foreign matter from lithium battery silicon-based negative electrode powder according to claim 1, characterized in that: The fixed base is equipped with an aeration device, which has a plurality of aeration ports located in the ultrasonic medium tank.

6. The device for separating magnetic foreign matter from lithium battery silicon-based negative electrode powder according to claim 1, characterized in that: The fixed base is provided with a cooling water channel for injecting cooling water into the ultrasonic medium tank, and / or the fixed base is provided with a dispersant pipeline connected to the dispersant inlet and a cleaning agent pipeline connected to the cleaning agent inlet.

7. The device for separating magnetic foreign matter from lithium battery silicon-based negative electrode powder according to any one of claims 1 to 6, characterized in that: The fixed base is equipped with a drive device that drives the separation processing unit to rotate.

8. A method for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries, characterized in that: The separation method is based on the magnetic foreign matter separation device for lithium battery silicon-based negative electrode powder according to claim 1, and the separation method includes the following steps: Step s1: Clean the separation device and observe its cleanliness. If there are obvious solid impurities attached, repeat the cleaning until the cleanliness of the separation device meets the standard. Step s2: Filling materials: A certain amount of silicon-based negative electrode powder and several magnetic rods are loaded into the processing chamber, and the sealing of the processing chamber is ensured. Step s3: Pre-disperse the silicon-based anode material from step s2, start the ultrasonic unit, rotate the processing chamber into the ultrasonic medium tank, add a certain proportion of organic dispersant into the buffer chamber through the dispersant inlet, and connect the buffer chamber and the processing chamber to allow the organic dispersant to be input into the processing chamber to wet the silicon-based anode powder. Step s4: Separate the pre-dispersed silicon-based anode powder from step s3. The processing chamber rotates back and forth, causing the material in the processing chamber to be in an intermittent tumbling motion. The original agglomerates of the silicon-based anode powder are deagglomerated and dispersed under the combined action of wetting by the organic dispersant, ultrasonic assisted cavitation, and friction and shearing generated by the rolling of the magnetic rod, so that the magnetic foreign matter is completely exposed and adsorbed on the surface of the magnetic rod. Step s5: The treatment liquid containing silicon-based negative electrode powder after separation in step s4 is input into the ultrasonic medium tank through the first discharge port and discharged out of the ultrasonic medium tank through the drain port. Then, the cleaning agent is input into the buffer chamber through the cleaning agent inlet to clean the organic dispersant remaining on the magnetic rod. After cleaning, the treatment chamber and the ultrasonic medium tank are connected, and then the waste liquid after cleaning is discharged out of the ultrasonic medium tank through the drain port. Step s6: Take out the cleaned magnetic rod from step s5 and transfer it to a digestion tube. Digest it with 50% aqua regia at 100°C for 60 minutes. Then dilute the resulting solution and perform quantitative analysis on the content of magnetic foreign matter.

9. The method for separating magnetic foreign matter from lithium battery silicon-based anode powder according to claim 8, characterized in that: In step s5, during the process of the treatment liquid being input into the ultrasonic media tank and discharged through the drain port, an aeration device is used to aerate the treatment liquid; and / or The separation method further includes: Step 7: Clean the processing chamber and buffer chamber after use until they are cleaned to the required standard. Then, discharge the waste liquid after cleaning out of the ultrasonic medium tank through the drain port.

10. The method for separating magnetic foreign matter from silicon-based negative electrode powder for lithium batteries according to claim 8, characterized in that: The organic dispersant in step s3 is a solution prepared from triethanolamine and water, with a volume ratio of triethanolamine to water of 1:3; and / or, The mass ratio of silicon-based anode powder to organic dispersant is between 20% and 200%.

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