Magnetic separation device and separation method for negative electrode materials

Abstract

The present invention provides a magnetic separation device and separation method for negative electrode materials, the magnetic separation device includes a fluidized shell with a fluidized chamber, the fluidized shell is provided with an air inlet and an air outlet connected to the fluidized chamber, and the air outlet can be connected to an external negative pressure part; a material blocking part with a plurality of material blocking vents is provided in the fluidized chamber, the fluidized chamber is divided by the material blocking part into an upper chamber connected to a connecting channel, and a lower chamber connected to the air inlet, a material receiving part is provided in the lower chamber, and a magnetic component is rotatably arranged above the material receiving part, so that the negative electrode material is in a fluidized state, and the magnetic component is used to adsorb magnetic foreign matter. The magnetic separation device for negative electrode materials described in the present invention, by fluidizing the negative electrode material and then adsorbing the magnetic foreign matter through the magnetic component, is not only conducive to improving the separation efficiency and accuracy of the magnetic foreign matter, but also conducive to reducing pollution and reducing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to a magnetic separation device for negative electrode materials. The present invention also relates to a magnetic separation method for negative electrode materials. Background Art

[0002] The technical route of lithium battery product material system tends to be diversified, but the evaluation indicators and testing methods for electrode materials, electrolytes and diaphragms in the existing technology are still imperfect. Among them, magnetic foreign matter in electrode materials will affect the thermal stability and consistency of batteries, thereby reducing the safety performance of batteries. Therefore, it is particularly important to establish a magnetic foreign matter testing system suitable for electrode materials.

[0003] Silicon-based negative electrode powder has the physical properties of being lipophilic and hydrophobic, easy to agglomerate, and having a low density. The method for testing magnetic foreign matter in silicon-based negative electrode powder requires that the magnetic foreign matter be relatively completely and specifically adsorbed on the surface of the magnetic rod to achieve the purpose of separating the magnetic foreign matter from the negative electrode powder. In order to achieve the purpose of separation, the silicon-based negative electrode powder needs to be fully dispersed in the pre-set dispersion system so that the magnetic foreign matter is completely exposed, thereby facilitating the magnetic rod to adsorb the magnetic foreign matter.

[0004] However, the conventional dispersion systems such as pure water, ethanol and NMP (N-methylpyrrolidone) commonly used in the current magnetic separation of foreign matter methods are difficult to achieve effective dispersion. The force between particles is mainly gravity, and the agglomeration phenomenon is significant. Some magnetic foreign matter is not completely exposed, and the effective adsorption rate of the magnetic separation process is low, which leads to a certain degree of deviation between the test results and the true value. At the same time, the separation test process produces a large amount of suspended waste liquid with high processing costs, and the high cost of consumables such as dispersants and cleaning agents makes the cost of magnetic foreign matter separation high. Summary of the invention

[0005] In view of this, the present invention aims to provide a magnetic separation device for negative electrode materials to improve the separation efficiency of magnetic foreign matter and help reduce the separation cost.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A magnetic separation device for negative electrode materials, used to separate magnetic foreign matter in the negative electrode materials, the magnetic separation device comprising a fluidizing shell having a fluidizing chamber, the fluidizing shell being provided with an air inlet and an air outlet communicating with the fluidizing chamber, and the air outlet being able to communicate with an external negative pressure part;

[0008] A material blocking portion with a plurality of material blocking vents is provided in the fluidizing chamber, and the fluidizing chamber is divided by the material blocking portion into an upper chamber connected to the connecting channel, and a lower chamber connected to the air inlet, and a material receiving portion for supporting the negative electrode material is provided in the lower chamber, and a magnetic component rotatably arranged above the material receiving portion is provided to fluidize the negative electrode material, the magnetic component is used to absorb the magnetic foreign matter, and the material blocking portion is used to prevent the negative electrode material and the magnetic foreign matter from flowing into the upper chamber.

[0009] Furthermore, it also includes a buffer shell having a buffer cavity, and a communication channel for connecting the air outlet and the buffer cavity, the buffer shell is provided with an air outlet communicating with the buffer cavity, and the air outlet is communicated with the external negative pressure part;

[0010] The communication channel is provided with a pressure control part, and the pressure control part can open the communication channel when the pressure of the buffer chamber is lower than the pressure of the fluidizing chamber.

[0011] Furthermore, a drying part is provided at the air inlet, and the external airflow flows through the drying part and then enters the fluidizing chamber; and / or, a flow control valve for adjusting the flow of the airflow in the communicating channel is provided on the communicating channel.

[0012] Furthermore, the magnetic component includes a magnetic part for adsorbing the magnetic foreign matter, and two ends of the magnetic part are rotatably arranged in the lower cavity via a rotating shaft; the magnetic part and the rotating shaft are detachably connected.

[0013] Furthermore, the rotating shaft is driven to rotate by the airflow in the fluidizing chamber; and the rotating shaft is connected to a rotation speed detection unit for detecting the rotation speed of the rotating shaft.

[0014] Furthermore, it also includes a pressure detection unit for detecting the pressure in the fluidization chamber.

[0015] Furthermore, the material receiving portion includes a plurality of grids stacked and arranged along the height direction of the fluidizing chamber, and the mesh holes on two adjacent grids are stacked and staggered.

[0016] Furthermore, the fluidizing shell is provided with an opening and a cover for opening or closing the opening; and / or the communicating channel is provided with a flow detection unit for detecting the flow of airflow in the communicating channel.

[0017] Furthermore, a mounting plate is provided below the material receiving portion to separate the lower cavity into an upper and lower part, and a plurality of ventilation structures are provided on the mounting plate and penetrate the mounting plate; a connecting hole is provided in the ventilation structure to connect the upper and lower sides of the mounting plate.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The magnetic separation device for negative electrode materials described in the present invention can drive the external airflow to flow into the fluidizing chamber through the air inlet and blow onto the negative electrode material through the connection between the exhaust port of the fluidizing chamber and the external negative pressure part, so that the negative electrode material is in a fluidized state. The negative electrode material due to mechanical overlap and occlusal bonding can be dispersed by wind-driven shear force, which is conducive to completely exposing the magnetic foreign matter. The magnetic foreign matter in the fluidized state is adsorbed by the rotating magnetic component, which is conducive to improving the adsorption efficiency of the magnetic foreign matter, and the separation efficiency of the magnetic foreign matter can be improved. The entire separation process does not require the use of dispersants or surfactants in the prior art, which is conducive to reducing the separation cost. At the same time, the use of the separation device will not produce pollutants such as wastewater, which is in line with the concept of energy saving and environmental protection. In addition, by setting a material blocking part, it is conducive to preventing the negative electrode material from flowing out of the fluidizing chamber, thereby helping to improve the separation accuracy of the magnetic foreign matter.

[0020] Secondly, by setting a buffer chamber, a connecting channel and a pressure control part, and the pressure control part can open the connecting channel when the pressure of the buffer chamber is less than the pressure of the fluidizing chamber, the airflow can be buffered to prevent the negative electrode material from moving violently due to excessive airflow and adhering to the inner wall of the fluidizing chamber to affect the separation accuracy. By setting a drying part, it is beneficial to improve the dryness of the airflow, prevent the moisture carried in the air from wetting the material, affect the primary agglomeration breakage and material fluidization, and then help improve the separation accuracy of magnetic foreign matter. The flow control valve is convenient for adjusting the airflow on the connecting channel to meet the use requirements. The structure of the magnetic part and the rotating shaft is simple and easy to arrange and implement. The magnetic part is detachably connected to the rotating shaft, which is convenient for removing the magnetic part, so as to process the adsorbed magnetic foreign matter. By detecting the rotation speed of the rotating shaft, a reference is provided for adjusting the rotation speed of the magnetic part, so that the rotation speed of the magnetic part is within a reasonable range, thereby helping to improve the adsorption efficiency of magnetic foreign matter. As a preferred embodiment, a rotation speed detection part is provided on the rotating shaft to detect the rotation speed of the rotating shaft, which is conducive to improving the adsorption efficiency of the magnetic part on magnetic foreign matter.

[0021] Thirdly, the pressure detection unit is used to facilitate the pressure condition in the fluidization chamber. The structure of the multiple grids in the material receiving unit is simple, easy to arrange and implement, and has a good supporting effect on the negative electrode material. It is also conducive to the passage of airflow, thereby improving the fluidization effect of the negative electrode material. The setting of the opening facilitates the taking and placing of the magnetic components and the negative electrode material to obtain the adsorbed magnetic foreign matter; the setting of the flow detection unit can obtain the flow rate of the airflow, which can serve as a basis for adjusting the flow rate of the airflow, so that the flow rate of the airflow is within an appropriate range. The setting of multiple ventilation structures on the mounting plate is conducive to improving the fluidization efficiency and effect of the negative electrode material.

[0022] In addition, another object of the present invention is to provide a magnetic separation method for negative electrode materials, comprising first fluidizing the negative electrode material so that the negative electrode material is in a fluidized state, and adsorbing magnetic foreign matter in the negative electrode material by a rotating magnetic part to separate the magnetic foreign matter from the negative electrode material.

[0023] The magnetic separation method for negative electrode materials of the present invention realizes the separation of magnetic foreign matter by fluidizing the negative electrode materials and adsorbing the magnetic foreign matter through a magnetic member. It not only has good separation efficiency, but also has high separation accuracy, and has low separation cost, low pollution and good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 This is a schematic diagram of the structure of a magnetic separation device for negative electrode materials according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the mounting plate and the ventilation structure according to an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1. Fluidizing shell; 2. Buffer shell; 3. Mounting plate; 4. Ventilation structure; 5. Material receiving part; 6. Magnetic component; 7. Tachometer; 8. Pressure gauge; 9. Connecting pipeline; 10. Flow control valve; 11. Pressure control valve;

[0029] 100, upper cavity; 200, lower cavity; 300, buffer cavity;

[0030] 101. air inlet; 102. drying section; 103. opening;

[0031] 201, air outlet;

[0032] 601, rotating shaft; 602, clip; 603, magnetic member;

[0033] 901. Connecting pipe. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0035] In the description of the present invention, it should be noted that if there are terms indicating orientation or positional relationship such as "upper", "lower", "inner", "back", etc., they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, if there are terms such as "first", "second", etc., they are also used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0036] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0037] Embodiment 1

[0038] This embodiment relates to a magnetic separation device for negative electrode materials, which is used to separate magnetic foreign matter from negative electrode materials. The magnetic separation device includes a fluidizing shell 1 having a fluidizing chamber, and the fluidizing shell 1 is provided with an air inlet 101 and an air outlet connected to the fluidizing chamber, and the air outlet is used to connect to an external negative pressure part.

[0039] Among them, a material blocking part with multiple material blocking vents is provided in the fluidizing chamber, and the fluidizing chamber is divided by the material blocking part into an upper cavity 100 connected to the connecting channel, and a lower cavity 200 connected to the air inlet 101, and the lower cavity 200 is provided with a material receiving part 5 for supporting the negative electrode material, and a magnetic component 6 rotatably arranged above the material receiving part 5, so that the negative electrode material is in a fluidized state, the magnetic component 6 is used to absorb magnetic foreign matter, and the material blocking part is used to prevent the negative electrode material and magnetic foreign matter from flowing into the upper cavity 100.

[0040] Based on the above overall introduction, an exemplary structure of the magnetic separation device described in this embodiment is as follows Figure 1 As shown in . The negative electrode material in this embodiment can specifically be a lithium-ion battery silicon-based negative electrode powder. Of course, the negative electrode material can also be other negative electrode materials in the prior art that can be applied to the separation device. The fluidized shell 1 in this embodiment is columnar, and the fluidized chamber is also columnar in shape following the fluidized shell 1. It has a simple structure and is convenient for structural molding. The above-mentioned material blocking part specifically adopts a material blocking plate arranged at the top of the fluidized chamber. The material blocking plate is preferably made of nylon material to have a longer service life. In specific implementation, the mesh number of the material blocking plate is preferably 3000. Of course, the mesh number of the material blocking plate can also be determined according to the use requirements. The area of ​​the material blocking vent should meet the blocking requirements of the negative electrode material and the magnetic foreign matter, that is, the diameter of the material blocking vent is smaller than the minimum diameter of the negative electrode material and the magnetic foreign matter, so as to prevent the negative electrode material and the magnetic foreign matter from flowing out of the fluidized chamber through the material blocking vent, thereby affecting the separation accuracy of the magnetic foreign matter.

[0041] In this embodiment, the above-mentioned exhaust port is provided at the top of the fluidizing chamber. In order to improve the outflow effect of the gas in the upper cavity 100, the cross section of the upper cavity 100 in this embodiment is gradually reduced from bottom to top. The air inlet 101 in this embodiment is located at the bottom of the entire fluidizing shell 1. In order to improve the separation accuracy and ensure the drying of the airflow flowing into the fluidizing chamber, as a preferred embodiment, a drying section 102 is provided at the air inlet 101, and the external airflow flows through the drying section 102 and enters the fluidizing chamber. In specific implementation, the drying section 102 here can adopt a filter element with a drying function in the prior art, which is conducive to preventing the moisture carried in the air from wetting the negative electrode material, affecting the crushing of the primary agglomeration and the fluidization of the material. In addition, in addition to having a good drying effect, it also has the effect of improving the cleanliness of the airflow, thereby further improving the separation accuracy of magnetic foreign matter. In addition, the air outside the fluidizing shell 1 can be dried in advance using a dehumidifier so that the ambient humidity is lower than 40%.

[0042] As a preferred embodiment, the magnetic component 6 is located in the middle and upper part of the fluidizing chamber to correspond to the magnetic foreign matter exposed in the fluidized state. The magnetic component 6 includes a magnetic part 603 for adsorbing magnetic foreign matter, and the two ends of the magnetic part 603 are respectively arranged in the lower cavity 200 via the rotating shaft 601, wherein the magnetic part 603 and the rotating shaft 601 are detachably connected. The magnetic part 603 in this embodiment is preferably driven to rotate by the airflow flowing in the fluidizing chamber, which is not only conducive to reducing the setting of the driving device and reducing the production cost, but also enables the rotation speed of the magnetic part 603 to be related to the state of the airflow in the fluidizing chamber, so that the rotation speed of the magnetic part 603 can reflect the state of the airflow, and at the same time, it is also conducive to the rotation speed of the magnetic part 603 to adapt to the fluidized state of the negative electrode material, so as to have a higher adsorption efficiency. In addition, the adsorption of magnetic foreign matter during the rotation of the magnetic part 603 can realize dynamic adsorption, and the adsorption efficiency and accuracy of the magnetic foreign matter are improved by increasing the effective contact area with the magnetic foreign matter.

[0043] In terms of specific structure, Figure 1 As shown in , the magnetic member 603 adopts a permanent magnet sheet, which is conducive to increasing the adsorption area with the magnetic foreign matter, and thus can improve the adsorption efficiency of the magnetic member 603. The electromagnetic field strength of the permanent magnet sheet in this embodiment can be 6000±100Gauss. For example, the magnetic field strength of the permanent magnet sheet can be 5900Gauss, 6000Gauss or 6100Gauss. When the electromagnetic field strength of the permanent magnet sheet is too small, the adsorption efficiency for the magnetic foreign matter is low and the adsorption effect is poor. When the electromagnetic field strength of the permanent magnet sheet is too large, it will cause the magnetization of the negative electrode material, thereby affecting the separation accuracy of the magnetic foreign matter.

[0044] In addition, in this embodiment, a protective layer can be wrapped outside the permanent magnetic sheet. When it is implemented, the protective layer is made of polytetrafluoroethylene material, which is resistant to strong acid and is conducive to improving stability in use. In particular, when the permanent magnetic sheet is digested, it is beneficial to prevent the permanent magnetic sheet from being corroded by aqua regia. The rotating shaft 601 in this embodiment is made of non-metallic and non-magnetic materials. As a preferred rotating shaft 601, wood is used to prevent the contamination of the negative electrode material by factors such as aging. In order to facilitate the connection between the permanent magnetic sheet and the corresponding rotating shaft 601, two relatively arranged clips 602 are respectively provided at the ends of each rotating shaft 601, and the corresponding ends of the permanent magnetic sheet can be sandwiched between the two clips 602, and can be detachably connected to the two clips 602 via a connecting piece. The clip 602 here is also preferably made of wood. The permanent magnetic sheet is detachably connected by the clip 602 and the connecting piece, which is not only convenient for implementation, but also convenient for installation and disassembly. It can be understood that the material of the rotating shaft 601 and the clip 602 can also be selected according to the use requirements.

[0045] In order to facilitate the detection of the rotation speed of the rotating shaft 601, in this embodiment, a rotation speed detection unit for detecting the rotation speed of the rotating shaft 601 is connected to the rotating shaft 601. The rotation speed detection unit can adopt the tachometer 7 in the prior art. Preferably, when the rotation speed of the rotating shaft 601 is between 30rpm and 45rpm, it means that the magnetic foreign matter in the fluidized chamber is in a fluidized state, and the force between particles in the fluidized state is mainly repulsive force. The dispersion degree of the powdered negative electrode material is high, and the original agglomeration caused by mechanical overlap and occlusal bonding can be depolymerized and dispersed by wind shear force, and the magnetic foreign matter is completely exposed. And when the rotation speed of the permanent magnet sheet is between 30rpm and 45rpm, it is ensured that the permanent magnet sheet has sufficient contact time with the magnetic foreign matter in the negative electrode material, which is conducive to improving the adsorption efficiency of the magnetic foreign matter.

[0046] In order to facilitate the placement of negative electrode materials into the fluidizing chamber and the removal of the permanent magnet sheet. Figure 1 As shown in the figure, the fluidized housing 1 is provided with an opening 103 and a cover for opening or closing the opening 103. The cover is provided with a visual window, or the cover is made of a transparent material (such as fiberglass) to facilitate observation of the state of the negative electrode material in the fluidized chamber. When the negative electrode material starts to boil, it indicates that it is about to enter the fluidized state.

[0047] In this embodiment, one side of the cover body can be pivotally connected to the fluidizing shell 1, and the other side of the cover body can be locked on the fluidizing shell 1 via a locking structure. In addition, a sealing structure can be provided around the cover body to improve the sealing effect between the cover body and the fluidizing shell 1 when the cover body is in a closed state. In specific implementation, the locking structure can also adopt a snap-fit ​​structure such as a buckle in the prior art, as long as it meets the use requirements, and is not specifically limited here.

[0048] like Figure 1As shown in , the material receiving part 5 in this embodiment includes a plurality of grids stacked and arranged along the height direction of the fluidizing chamber, and the meshes on two adjacent grids are stacked and staggered. In this embodiment, the mesh number of the grid can be 2000 meshes, and the number of grids is four. The grid here is preferably made of nylon material to have better reliability in use. The stacking and staggered arrangement of the meshes on two adjacent grids in the up and down directions is beneficial to improving the supporting effect of the material receiving part 5 on the negative electrode material, and it is also beneficial for the airflow to flow through the negative electrode material from bottom to top, so that the negative electrode material is in a fluidized state. Of course, during specific implementation, the grid can be detachably installed in the fluidizing chamber, and the number of grids in the material receiving part 5 and the mesh number of the grid can be determined according to the use requirements.

[0049] In addition, in this embodiment, if Figure 1 As shown in , a mounting plate 3 is provided below the material receiving portion 5 to divide the lower cavity 200 into two parts, and a plurality of ventilation structures 4 are provided on the mounting plate 3 and penetrate the mounting plate 3. The ventilation structures 4 are provided with connecting holes for connecting the upper and lower sides of the mounting plate 3. Specifically, as Figure 2 As shown in , each ventilation structure 4 is roughly gourd-shaped, and the ventilation holes are also gourd-shaped along with the ventilation structure 4. Among them, the cross-sectional area of ​​the connecting hole located below the mounting plate 3 is smaller than the cross-sectional area of ​​the connecting hole located above the mounting plate.

[0050] In addition, the bottom opening 103 of the communicating hole is relatively small, and the top opening 103 of the communicating hole is relatively large. When the airflow flows into the bottom of the mounting plate 3, the airflow flows in through the bottom of the communicating hole, and the flow area gradually increases, which is conducive to increasing the blowing area of ​​the airflow, thereby improving the fluidization efficiency of the negative electrode material. At the same time, in this embodiment, the negative electrode material is blown by multiple ventilation structures 4, which is conducive to further improving the fluidization efficiency of the negative electrode material.

[0051] The magnetic separation device in this embodiment also includes a buffer shell 2 having a buffer cavity, and a connecting channel for connecting the exhaust port and the buffer cavity 300. The buffer shell 2 is provided with an air outlet 201 connected to the buffer cavity 300, and the air outlet 201 is connected to the external negative pressure part. In other words, the exhaust port is connected to the external negative pressure part via the connecting channel and the air outlet 201 on the buffer cavity 300. In this embodiment, the structure of the buffer shell 2 is as follows: Figure 1As shown in , the top of the buffer shell 2 is provided with a through hole connected to the buffer chamber 300 body, one end of the connecting channel is connected to the air outlet 201, and the other end of the connecting channel is connected to the buffer chamber 300 body via the through hole. Specifically, the connecting channel includes a connecting pipe 9 connected to the through hole at one end, and a connecting pipe 9 connected to the air outlet via a connecting pipe 901 at one end, and the two connecting pipes 9 are connected via the connecting pipe 901. That is, the two sections of the connecting pipe 9 cooperate with the two connecting pipes 901 to form the above-mentioned connecting channel. Preferably, the connecting pipe 9 and the connecting pipe 901 are detachably connected, for example, connected by screwing, so as to facilitate the processing of each part. Of course, during the specific implementation, the structure and connection method of the connecting channel can also be determined according to the use requirements, and are not limited to the structural method shown in the figure.

[0052] In order to improve the effect of airflow into the buffer chamber 300, the cross-sectional area of ​​the top of the buffer chamber 300 is gradually increased in the vertical downward direction. The air outlet 201 is set at the bottom of the buffer shell 2, and the external negative pressure part can be a vacuum pump in the prior art. When the vacuum pump is turned on, the pressure in the buffer chamber 300 can be reduced first, and when the pressure in the fluidizing chamber is greater than the pressure in the buffer chamber 300, the external airflow is driven to flow into the fluidizing chamber through the air inlet 101, and then flow into the buffer chamber 300 through the connecting pipe 9. The buffer chamber 300 here is conducive to buffering the airflow, thereby reducing the influence of airflow fluctuations on the fluidization of materials and improving the separation efficiency and accuracy of magnetic foreign matter.

[0053] As a preferred embodiment, a pressure control unit is provided on the communication channel, and the pressure control unit can open the communication channel when the pressure of the buffer chamber 300 is lower than the pressure of the fluidizing chamber. In this embodiment, the pressure control unit cooperates with the buffer chamber 300 to improve the buffering effect of the air flow and prevent the occurrence of low precision of magnetic foreign matter adsorption caused by fluctuations in air flow velocity. Figure 1 As shown in , the pressure control part here can adopt a pressure control valve 11 arranged on the connecting pipeline 9, and the pressure control valve 11 here can adopt a mature product in the prior art. When the pressure in the buffer chamber 300 drops to the target pressure, the pressure control valve 11 opens, so that the airflow in the fluidizing chamber can flow into the buffer chamber 300 through the connecting channel. In specific implementation, the pressure control valve 11 can be opened when the pressure in the buffer chamber 300 reaches 0.01Mpa, which is conducive to controlling the flow rate of the airflow, thereby improving the fluidization effect of the negative electrode material. Of course, the opening target pressure of the pressure control valve 11 can still be determined according to the use requirements.

[0054] In addition, Figure 1As shown in , a flow control valve 10 for adjusting the flow of the airflow in the connecting channel is provided on the connecting channel. The flow control valve 10 is beneficial to increase the flow rate and flow velocity of the airflow, and further to improve the fluidization state of the negative electrode material. A flow detection unit for detecting the flow rate of the airflow in the connecting channel is provided on the connecting channel, so as to detect the flow rate as the basis for adjusting the airflow. The flow detection unit here can adopt a flow meter in the prior art, which is a mature product, easy to arrange and implement, and has a good detection effect. In order to determine the pressure in the fluidizing chamber, the magnetic separation device in this embodiment also includes a pressure detection unit for detecting the pressure in the fluidizing chamber. The pressure detection unit can adopt a pressure gauge 8 or a pressure sensor in the prior art.

[0055] In addition, in order to reduce the adsorption of magnetic foreign matter by the inner wall of the fluidizing chamber, the inner wall of the fluidizing chamber is preferably made of polytetrafluoroethylene. Before using the separation device, check the air tightness of the device and demagnetize the fluidizing chamber. The permanent magnet sheet is soaked in 50% aqua regia for 60 minutes to prevent the magnetic particles attached to the permanent magnet sheet from affecting the accuracy of the test results. The ambient humidity is controlled below 40% by a dehumidifier to prevent the moisture carried in the air from wetting the material and affecting the crushing of the primary agglomerates and the fluidization of the material.

[0056] When the magnetic separation device for negative electrode materials described in this embodiment is used, the following steps are performed:

[0057] The first step: open the cover, place the pre-weighed silicon-based negative electrode powder on the grid through the opening 103, install the permanent magnet sheet on the rotating shaft 601, and then close the cover.

[0058] Step 2: Turn on the vacuum pump and the flow control valve 10. When the internal pressure of the buffer chamber 300 is reduced to the opening condition PMax of the pressure control valve 11, the pressure control valve 11 is in the open state.

[0059] Step 3: The pressure difference between the pressure P2 in the fluidizing chamber and the pressure P1 in the buffer chamber 300 is rapidly reduced to 0, so that the fluidizing chamber is in a negative pressure state, and there is a pressure difference with the external environment to which it is connected.

[0060] Step 4: With the pressure difference between the fluidizing chamber and the outside of the fluidizing chamber as the driving force, the airflow in the external environment flows through the drying part 102 in the air inlet for drying, and the dried airflow is blown to the silicon-based negative electrode powder on the grid through the connecting holes.

[0061] Step 5: Observe the material state in the fluidization chamber through the cover plate, and adjust the vacuum pump power until the air flow rate reaches the fluidization speed required by the negative electrode material, and the negative electrode material begins to boil and enters the fluidization state.

[0062] Step 6: Adjust the flow control valve 10 until the rotation speed of the permanent magnet sheet is between 30 rpm and 45 rpm, so as to ensure that the permanent magnet sheet and the magnetic foreign matter in the negative electrode material have sufficient contact time.

[0063] Step 7: After the flow value displayed by the flow meter stabilizes, maintain the fluidization working state for 30 minutes, then close the flow control valve 10, and the fluidization process is completed.

[0064] Step 8: Turn off the vacuum pump and let the entire separation device stand for 10 minutes to prevent the fine dust resulting from the strong pneumatic shear force from escaping and causing harm to the staff.

[0065] Step 9: Open the cover, disassemble the permanent magnet sheet and transfer it to a digestion tube, digest it in 20 ml of 50% aqua regia for 90 minutes, dilute the resulting solution and quantitatively analyze the content of magnetic foreign matter by ICP-OES (inductively coupled plasma emission spectrometer), then disassemble the grid, scrap the negative electrode material and clean the grid.

[0066] The magnetic separation device for negative electrode materials described in this embodiment can drive the external airflow to flow into the fluidizing chamber through the air inlet 101 and blow onto the negative electrode material through the connection between the fluidizing chamber and the external negative pressure part, so that the negative electrode material is in a fluidized state. In the fluidized state, the force between the particles of the negative electrode material is mainly repulsive force, the dispersion degree of the negative electrode material is high, and the original agglomerates caused by mechanical overlap and bite bonding can be deagglomerated and dispersed by wind-driven shear force, and the magnetic foreign matter is completely exposed. The magnetic foreign matter in the fluidized state is adsorbed by the rotating magnetic component 6, which is beneficial to improve the adsorption efficiency of the magnetic foreign matter, and can improve the separation efficiency of the magnetic foreign matter.

[0067] In this embodiment, the air flow velocity is regulated at two levels by the power of the vacuum pump and the flow control valve 10, so that the controllability of the fluidized state of the negative electrode material is further improved. And the entire separation process does not require the use of dispersants or surfactants in the prior art, which helps to reduce the separation cost. At the same time, the use of the separation device does not produce pollutants such as wastewater, which is in line with the concept of energy conservation and environmental protection. Moreover, by setting a material blocking part, it is helpful to prevent the negative electrode material from flowing out of the fluidization chamber, thereby helping to improve the separation accuracy of magnetic foreign matter.

[0068] Embodiment 2

[0069] The present embodiment relates to a magnetic separation method for negative electrode materials, which includes first subjecting the negative electrode materials to fluidization treatment so that the negative electrode materials are in a fluidized state, and then absorbing magnetic foreign matter in the negative electrode materials by a rotating magnetic member 603, thereby separating the magnetic foreign matter from the negative electrode materials.

[0070] In specific implementation, the magnetic separation method for negative electrode materials can use the magnetic separation device for negative electrode materials described in Example 1 to perform the above separation steps. The specific process refers to the method for using the separation device in Example 1, which will not be described in detail here.

[0071] The magnetic separation method for the negative electrode material described in this embodiment achieves separation of magnetic foreign matter by fluidizing the negative electrode material and adsorbing the magnetic foreign matter through the magnetic member 603. It not only has good separation efficiency, but also has high separation accuracy, and has low separation cost, low pollution, and good practicality.

[0072] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetic separation device for negative electrode materials, used to separate magnetic foreign matter from negative electrode materials, characterized in that: The magnetic separation device comprises a fluidizing shell having a fluidizing cavity, the fluidizing shell is provided with an air inlet and an air outlet communicating with the fluidizing cavity, and the air outlet can be communicated with an external negative pressure part; The fluidizing chamber is provided with a material blocking portion having a plurality of material blocking vents, the fluidizing chamber is divided by the material blocking portion into an upper chamber connected to the exhaust port, and a lower chamber connected to the air inlet, and the lower chamber is provided with a material receiving portion for supporting the negative electrode material, and a magnetic component is rotatably arranged above the material receiving portion, so that the negative electrode material is in a fluidized state, the magnetic component is used to absorb the magnetic foreign matter, and the material blocking portion is used to prevent the negative electrode material and the magnetic foreign matter from flowing into the upper chamber; It also includes a buffer shell having a buffer cavity, and a communication channel for connecting the air outlet and the buffer cavity, the buffer shell is provided with an air outlet communicating with the buffer cavity, and the air outlet is communicated with the external negative pressure part; The communicating channel is provided with a pressure control unit, and the pressure control unit can open the communicating channel when the pressure of the buffer chamber is lower than the pressure of the fluidizing chamber, and drive the external airflow to flow into the fluidizing chamber through the air inlet.

2. The magnetic separation device for negative electrode materials according to claim 1, characterized in that: The air inlet is provided with a drying section, and the external airflow flows through the drying section and then enters the fluidizing chamber; and / or, The communication channel is provided with a flow control valve for adjusting the flow of the airflow in the communication channel.

3. The magnetic separation device for negative electrode materials according to claim 1, characterized in that: The magnetic component comprises a magnetic member for adsorbing the magnetic foreign matter, and two ends of the magnetic member are respectively rotatably disposed in the lower cavity via a rotating shaft; The magnetic member and the rotating shaft are detachably connected.

4. The magnetic separation device for negative electrode materials according to claim 3, characterized in that: The rotating shaft is driven to rotate by the airflow in the fluidizing chamber; The rotating shaft is connected with a rotation speed detection unit for detecting the rotation speed of the rotating shaft.

5. The magnetic separation device for negative electrode materials according to claim 1, characterized in that: It also includes a pressure detection unit for detecting the pressure in the fluidization chamber.

6. The magnetic separation device for negative electrode materials according to claim 1, characterized in that: The material receiving part comprises a plurality of grids which are stacked and arranged along the height direction of the fluidizing chamber, and the mesh holes on two adjacent grids are stacked and staggered.

7. The magnetic separation device for negative electrode materials according to claim 1, characterized in that: The fluidizing shell is provided with an opening and a cover for opening or closing the opening; and / or, The communicating channel is provided with a flow detection portion for detecting the flow of airflow in the communicating channel.

8. The magnetic separation device for negative electrode materials according to any one of claims 1 to 7, characterized in that: A mounting plate is provided below the material receiving portion to separate the lower cavity into an upper and lower part, and a plurality of ventilation structures are provided on the mounting plate and penetrate the mounting plate; The ventilation structure is provided with a connecting hole for connecting the upper and lower sides of the mounting plate.

9. A magnetic separation method for negative electrode materials, characterized in that: The magnetic separation device for negative electrode materials according to claim 1, wherein the magnetic separation method comprises first subjecting the negative electrode materials to fluidization treatment so that the negative electrode materials are in a fluidized state, and absorbing magnetic foreign matter in the negative electrode materials by a rotating magnetic part, thereby separating the magnetic foreign matter from the negative electrode materials.

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