Recycling method of lithium iron phosphate of battery pole piece

Abstract

The invention provides a recovery method of lithium iron phosphate of a battery pole piece, and relates to the technical field of batteries. The recovery method of lithium iron phosphate of the battery pole piece comprises the following steps: crushing the pole piece to obtain a crushed material; sieving the crushed material to obtain a primarily sieved material; grinding treatment is conducted on the primarily-screened material through grinding equipment, a ground material is obtained, and the ground material comprises a metal foil and lithium iron phosphate powder; and the ground material is sieved, the metal foil and the lithium iron phosphate powder are separated, the lithium iron phosphate powder is obtained, and therefore the recycling efficiency and the recycling quality of lithium iron phosphate are improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for recovering lithium iron phosphate from battery pole pieces. Background Art

[0002] Lithium iron phosphate batteries are lithium-ion batteries that use lithium iron phosphate as the positive electrode material and carbon as the negative electrode material. The lithium iron phosphate electrode typically uses a metal foil, such as aluminum foil, as the current collector. Lithium iron phosphate batteries offer advantages such as high operating voltage, high energy density, long cycle life, excellent safety, low self-discharge, and no memory effect.

[0003] Failure to effectively recycle the lithium iron phosphate (LiFePO4) from the electrodes of used lithium iron phosphate (LFP) batteries not only wastes resources but also pollutes the environment. Conventional techniques typically mechanically separate the LiFePO4 from the electrodes. However, this separation is incomplete, leaving residual LiFePO4 on the electrodes and resulting in low recycling efficiency. Summary of the Invention

[0004] The present application provides a method for recovering lithium iron phosphate from battery pole pieces to solve the problem of low recovery efficiency of lithium iron phosphate from lithium iron phosphate battery pole pieces, thereby improving the recovery efficiency of lithium iron phosphate.

[0005] The present application provides a method for recovering lithium iron phosphate from battery pole pieces, comprising:

[0006] Crushing the pole pieces to obtain crushed materials;

[0007] sieving the crushed material to obtain a primary screened material;

[0008] Grinding the pre-screened material with a grinding device to obtain a ground material, wherein the ground material includes metal foil and lithium iron phosphate powder;

[0009] The ground material is sieved to separate the metal foil and the lithium iron phosphate powder to obtain the lithium iron phosphate powder.

[0010] Through the above scheme, the recovery method of lithium iron phosphate of battery pole pieces provided by the present application is to first crush the pole piece to obtain a crushed material, then screen the crushed material to obtain a pre-screened material, and then grind the pre-screened material through a grinding device to obtain a ground material. Since the metal has good ductility, the metal material in the pre-screened material will form metal foil under the grinding action of the grinding device, and since lithium iron phosphate is an inorganic compound, the lithium iron phosphate in the pre-screened material will form lithium iron phosphate powder with a smaller particle size under the grinding action of the grinding device. After the grinding device grinds the pre-screened material, a mixture containing metal foil and lithium iron phosphate powder can be obtained. The ground material is then screened to effectively separate the metal foil and the lithium iron phosphate powder to obtain lithium iron phosphate powder. Compared with the scheme of mechanically stripping lithium iron phosphate from the pole piece in the prior art, the phenomenon of lithium iron phosphate residue on the pole piece is avoided to a certain extent, and the effective recovery of lithium iron phosphate material is achieved, the recovery efficiency of lithium iron phosphate is improved, and the recovery purity is high.

[0011] At the same time, compared with the solution of using a large amount of chemical reagents to recycle lithium iron phosphate materials, it not only reduces the recycling cost, but also avoids the environmental pollution caused by chemical reagents and the corrosion of metal foil by chemical reagents, which is conducive to the subsequent recycling of metals.

[0012] In a possible design, the grinding device has a roller structure therein, and the roller structure is used to grind the pre-screened material to obtain the metal foil and lithium iron phosphate powder.

[0013] The above solution provides a roller structure within the grinding equipment, which is simple and easy to implement. The roller structure is used to grind the pre-screened material, causing the metal material in the pre-screened material to form metal foil under the grinding action of the roller structure. Furthermore, the lithium iron phosphate in the pre-screened material is also ground into lithium iron phosphate powder with a smaller particle size under the grinding action of the roller structure. This separates the lithium iron phosphate from the metal foil, achieving separation of the lithium iron phosphate from the electrode, with high separation efficiency.

[0014] In one possible design, the roller structure includes at least one fixed roller and at least two rotating rollers, the fixed roller and the rotating rollers are arranged in a horizontal direction, and a fixed roller is arranged between at least two adjacent rotating rollers, and the roller gap between adjacent fixed rollers and rotating rollers is 10μm-200μm, and the roller gap between two adjacent rotating rollers is 10μm-200μm.

[0015] Through the above scheme, the roller structure includes at least one fixed roller and at least two rotating rollers, the fixed rollers and the rotating rollers are arranged in the horizontal direction, and a fixed roller is arranged between at least two adjacent rotating rollers, and the roller gap between the fixed roller and the adjacent rotating roller is 10μm-200μm, and the roller gap between the rotating roller and the adjacent rotating roller is 10μm-200μm. The structure is simple and easy to manufacture. Under the action of the rotating roller, the primary screened material is continuously brought into the roller gap and is subjected to a gradually increasing extrusion and grinding force in the process of being forced to move downward, so that the particle size of the lithium iron phosphate powder and the particles is smaller, and the metal material is extended into a larger metal foil, thereby increasing the particle size difference between the lithium iron phosphate powder and the metal foil, having a better grinding effect on the primary screened material, facilitating the grinding and separation of the lithium iron phosphate powder, and helping to improve the separation efficiency and recovery efficiency of the lithium iron phosphate powder.

[0016] In a possible design, the two outermost rollers of the roller structure in the horizontal direction are both rotating rollers, and when viewed from above in the horizontal direction, the rotation direction of the two outermost rotating rollers is inward.

[0017] Through the above scheme, the two rollers located on the outermost sides of the roller structure in the horizontal direction are both rotating rollers, and when viewed from above in the horizontal direction, the rotation direction of the two rotating rollers located on the outermost sides is inward. That is to say, the roller structure located on the outermost sides in its arrangement direction is the rotating roller, and when viewed from above in the arrangement direction, the rotation direction of the two rotating rollers located on the outermost sides of the roller structure in its arrangement direction is inward. In this way, after the pre-screened material enters the grinding equipment, it can move toward the inner side of the roller structure and can be continuously brought into the roller gap for grinding. To a certain extent, the pre-screened material is avoided from accumulating on the inner wall of the grinding equipment above the roller structure. The reasonable design helps to improve the grinding efficiency and reduce the residue of the pre-screened material in the grinding equipment.

[0018] And / or, the grinding pressure of the rotating roller is 50T-200T.

[0019] Through the above scheme, the grinding pressure of the rotating roller is set to 50T-200T, so that the primary screened material is subjected to a higher roller pressure at the roller gap. Under the action of high pressure, on the one hand, the lithium iron phosphate powder and particles in the primary screened material are broken to form materials with smaller particle size. On the other hand, the metal materials in the primary screened material, such as metal fragments, are stretched and deformed into larger metal foils, further improving the grinding efficiency of the roller structure.

[0020] And / or, the rotation speed of the rotating roller is 1 m / s-5 m / s.

[0021] Through the above scheme, the rotation speed of the rotating roller is set to 1m / s-5m / s. While ensuring that the contact time of the primary screened material at the roller gap is the same, the number of times the primary screened material is ground per unit time is increased, thereby improving the grinding efficiency, and further making the recovery efficiency of lithium iron phosphate powder higher.

[0022] In a possible design, the roller structure has at least two levels, and the at least two levels of roller structures are arranged in sequence along the vertical direction, and the roller gaps of the two adjacent levels of roller structures are staggered in the vertical direction;

[0023] Through the above scheme, the grinding equipment includes a multi-stage roller structure, and the multi-stage roller structure is arranged in sequence along the vertical direction, and the roller gaps of the two adjacent roller structures above and below are staggered in the vertical direction. In other words, the roller gap of the upper roller structure and the roller gap of the lower roller structure will not overlap in the vertical direction, so that the positive projection of the roller gap of the upper roller structure is located on the fixed roller or rotating roller of the lower roller structure. With such an arrangement, the grinding material will not directly enter the roller gap of the lower roller structure after falling from the roller gap of the upper roller structure, which increases the contact time between the grinding material and the roller structure, thereby improving the grinding efficiency and further improving the recovery rate of the lithium iron phosphate powder.

[0024] And / or, the grinding pressure of the grinding equipment is 50T-200T;

[0025] And / or, the grinding equipment includes a roller press.

[0026] Through the above solution, the grinding equipment is set as a roller press, which has a simple structure, is easy to implement and has low cost.

[0027] In a possible design, the grinding equipment performs at least two-stage grinding treatment on the pre-screened material.

[0028] Through the above scheme, the grinding equipment performs at least two-stage grinding treatment on the primary screened material, so that the primary screened material will be ground and processed at least twice after entering the grinding equipment. That is to say, the ground material generated by the previous stage of grinding will enter the next stage to continue to be ground and processed, which increases the grinding processing time of the primary screened material, thereby improving the grinding efficiency, and further improving the recovery rate of lithium iron phosphate powder.

[0029] In a possible design, the pole pieces are crushed by a crushing structure.

[0030] Through the above scheme, the electrode is crushed using a crushing structure to generate crushed materials such as powder, fragments, and particles. The structure is simple, easy to implement, low cost, and has high crushing efficiency, and the electrode is crushed more fully.

[0031] And / or, the crushed material is screened through a first vibrating screen.

[0032] Through the above scheme, the first vibrating screen is used to vibrate and screen the crushed material. Through the high-frequency vibration of the first vibrating screen, the crushed material will produce strong jumping and sliding, which can quickly separate crushed materials of different particle sizes, so that the smaller part of the crushed material passes through the screen holes of the first vibrating screen to generate primary screening materials, and the larger part of the crushed material is screened out and remains above the first vibrating screen. The screening efficiency is high, and it is not easy to get clogged, thereby improving the stability and reliability of operation. In addition, the structure is simple, easy to implement, and low cost.

[0033] The mesh number of the first vibrating screen is not greater than 80 mesh;

[0034] By setting the mesh number of the first vibrating screen to no more than 80 meshes, that is, the mesh number of the first vibrating screen is smaller, so that under the condition of the same length, the first vibrating screen has fewer sieve holes and a larger aperture, so that the crushed material with the required particle size can pass through the sieve holes more fully to enter the subsequent grinding process, the screening efficiency is high, which facilitates the effective recovery of lithium iron phosphate materials and helps to improve the recovery efficiency of lithium iron phosphate.

[0035] and / or, screening the ground material through a second vibrating screen;

[0036] Through the above scheme, the grinding material is screened by the second vibrating screen. Through the high-frequency vibration of the second vibrating screen, the grinding material will produce strong jumping and sliding, which can quickly separate the metal foil and the lithium iron phosphate powder, and make the lithium iron phosphate powder pass through the sieve holes of the second vibrating screen and be effectively recovered, and the metal foil is screened out and left above the second vibrating screen. The screening efficiency is high and it is not easy to get clogged, thereby improving the stability and reliability of operation. In addition, the structure is simple, the operation is convenient, it is easy to implement and the cost is low.

[0037] The mesh number of the second vibrating screen is 100-120 mesh.

[0038] By setting the mesh size of the second vibrating screen to 100-120 mesh, the number and aperture of the second vibrating screen are more appropriate when the length is the same, so that the powder in the grinding material can pass through the screen holes, and the metal foil can be screened out and left above the second vibrating screen, thereby achieving effective recovery of lithium iron phosphate powder, and the recovery purity is higher and the recovery effect is better.

[0039] In one possible design, the method for recovering lithium iron phosphate from the battery electrode further includes:

[0040] The lithium iron phosphate powder is transported to a storage bin through a first conveying line.

[0041] Through the above scheme, a storage bin is set up, and the lithium iron phosphate powder obtained by screening the ground material is transported to the storage bin through the first conveyor line, thereby realizing the automatic recovery and storage of the lithium iron phosphate powder, improving the degree of automation of lithium iron phosphate powder recovery, and making recovery more convenient.

[0042] In one possible design, at least one fool-proof structure is provided on the first conveyor line, the fool-proof structure being electrically connected to the first conveyor line, the fool-proof structure being used to detect the lithium iron phosphate powder, and the first conveyor line being used to stop when the fool-proof structure detects metallic foreign matter in the lithium iron phosphate powder;

[0043] The foolproof structure includes a cleanliness analyzer.

[0044] Through the above scheme, an anti-foolproof structure is set on the first conveyor line, and the lithium iron phosphate powder is detected by the anti-foolproof structure. Moreover, the first conveyor line can stop conveying the lithium iron phosphate powder into the storage bin when the anti-foolproof structure detects metal foreign matter in the lithium iron phosphate powder. The degree of automation is high, the use is convenient, and the recovery efficiency of the lithium iron phosphate powder is guaranteed to a certain extent.

[0045] In one possible design, the method for recovering lithium iron phosphate from the battery electrode further includes:

[0046] When the fool-proof structure detects that there are metallic foreign objects in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line is returned to the grinding equipment through the second conveyor line to be ground again.

[0047] Through the above scheme, when the fool-proof structure detects that there are metal foreign objects in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line can be returned to the grinding equipment through the second conveyor line, so that the grinding equipment can continue to grind the returned lithium iron phosphate powder, further improving the degree of automation of lithium iron phosphate powder recovery and the recovery efficiency of lithium iron phosphate powder, and ensuring the recovery quality of lithium iron phosphate powder.

[0048] In one possible design, the method for recovering lithium iron phosphate from the battery electrode further includes:

[0049] An element test is performed on the lithium iron phosphate powder in the storage bin, and when the aluminum content is greater than a first preset threshold and / or the copper content is greater than a second preset threshold, the operating parameters of the grinding equipment are adjusted.

[0050] Through the above scheme, the lithium iron phosphate powder in the storage bin is subjected to elemental testing to determine whether the aluminum content is greater than the first preset threshold and / or whether the copper content is greater than the second preset threshold. That is, by detecting whether the aluminum content and copper content in the recovered lithium iron phosphate powder meet the standards, the working parameters of the grinding equipment are adjusted, thereby further improving the recovery purity and recovery efficiency of the lithium iron phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a flow chart of the steps of the method for recovering lithium iron phosphate from battery electrodes according to one embodiment of the present application.

[0052] Figure 2 A structural schematic diagram of recycling lithium iron phosphate using the lithium iron phosphate recycling method for battery pole pieces described in one embodiment of the present application.

[0053] Figure 3 for Figure 2 Enlarged view of point A in the middle.

[0054] Figure 4 This is a flow chart of another step of the method for recovering lithium iron phosphate from battery electrodes described in one embodiment of the present application.

[0055] Figure 5 This is a bar chart showing the test results of the aluminum content and copper content in the lithium iron phosphate powder obtained by the method for recovering the lithium iron phosphate of the battery electrode described in the embodiment of the present application and the aluminum content and copper content in the lithium iron phosphate powder obtained by the prior art.

[0056] Figure 6 Schematic diagram comparing the processing performance and electrical properties of lithium iron phosphate powder obtained by the method for recovering lithium iron phosphate of battery pole pieces described in the embodiment of the present application with the processing performance and electrical properties of lithium iron phosphate powder obtained by the prior art.

[0057] Explanation of the accompanying symbols: 1. Crushing structure; 11. Connecting rod; 12. Blade; 2. First vibrating screen; 3. Grinding equipment; 4. Second vibrating screen; 5. Anti-fool structure; 6. Storage bin; 7. First conveyor line; 8. Second conveyor line; 9. Roller structure; 91. Fixed roller; 92. Rotating roller. DETAILED DESCRIPTION

[0058] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification, claims and drawings of this application are intended to cover non-exclusive inclusions.

[0060] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0061] The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists, A and B exist, and B exists. Additionally, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0062] The directional words appearing in the following description are all directions shown in the drawings, and do not limit the specific structure of the equipment used in the method for recycling lithium iron phosphate of battery pole pieces of the present application. For example, in the description of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application.

[0063] In addition, the terms "first", "second", etc. in the description and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order, and may explicitly or implicitly include one or more such features.

[0064] In the description of this application, unless otherwise specified, "plurality" means more than two (including two), and similarly, "multiple groups" means more than two (including two).

[0065] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, "connected" or "connected" in a mechanical structure can refer to a physical connection. For example, a physical connection can be a fixed connection, such as a fixed connection via screws, bolts, or other spacers; a physical connection can also be a removable connection, such as a snap-fit connection; or an integral connection, such as a connection formed by welding, bonding, or integral molding. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances. "Connected" or "connected" in a circuit structure can refer not only to a physical connection, but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate component, as long as circuit connectivity is achieved. It can also refer to internal communication between two components. A signal connection can refer not only to signal connection through an electrical circuit, but also to signal connection through a media medium, such as radio waves. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0066] refer to Figures 1 to 4 As shown, this embodiment provides a method for recovering lithium iron phosphate from battery pole pieces, and the method for recovering lithium iron phosphate from battery pole pieces includes:

[0067] S101, crushing the electrode to obtain crushed material.

[0068] By comminuting the pole pieces, the pole pieces are broken into powder, fine fragments, and fine particles, which are easy to process and help improve the recovery efficiency of the lithium iron phosphate material in the pole pieces. The fragments and particles are relatively small, typically ranging from millimeters to microns.

[0069] In addition, the electrode is crushed so that non-metallic materials such as lithium iron phosphate on the electrode fall off from the metal foil to a certain extent, making it easier to separate non-metallic materials such as lithium iron phosphate from metal impurities in the subsequent process.

[0070] In some embodiments, reference Figure 2 As shown, for example, the pole piece can be crushed by the crushing structure 1 .

[0071] The electrode is crushed by using the crushing structure 1 to generate crushed materials such as powder, fragments, and particles. The structure is simple, easy to implement, low in cost, and has a high crushing efficiency. The electrode is crushed more fully.

[0072] In a specific implementation, the crushing structure 1 can be, for example, a jaw crusher, a hammer crusher, a scissors crusher, etc.

[0073] It should be noted that the above-mentioned electrode is a waste lithium iron phosphate electrode. The waste lithium iron phosphate electrode can be either an unused waste lithium iron phosphate electrode generated during the battery production process or a used lithium iron phosphate electrode from a waste battery.

[0074] The following embodiments are explained and illustrated by taking the unused waste lithium iron phosphate electrodes generated during the production process as an example.

[0075] S102, sieving the crushed material to obtain the primary screened material.

[0076] In a specific implementation, the pulverized material generated in step S101 is screened to allow smaller portions of the pulverized material, such as powder, smaller fragments, and particles, to pass through the sieve holes, forming the primary screened material and entering the subsequent steps to facilitate the recovery of the lithium iron phosphate material. Larger portions of the pulverized material, such as larger fragments and particles, are screened out to prevent them from flowing into the subsequent steps and affecting the subsequent grinding efficiency, thereby helping to improve the recovery efficiency of the lithium iron phosphate.

[0077] In some implementations, for example, the larger portion of the pulverized material that has been screened out can be added back into the pulverizing structure 1 for secondary pulverization. This not only avoids the waste of materials caused by incomplete pulverization of the electrode to a certain extent, but also improves the recovery efficiency of the lithium iron phosphate material to a certain extent.

[0078] For example, the crushed material generated in step S101 is screened, and the powder and smaller fragments and particles pass through the screening process and enter the subsequent steps. Larger fragments and particles do not pass through and are screened out and separated from the crushed material.

[0079] In some embodiments, reference Figure 2 As shown, for example, the crushed material generated in step S101 can be screened through the first vibrating screen 2 .

[0080] The first vibrating screen 2 is used to vibrate and screen the crushed material. Through the high-frequency vibration of the first vibrating screen 2, the crushed material will produce strong jumping and sliding, which can quickly separate the crushed materials of different particle sizes, so that the smaller part of the crushed material passes through the screen holes of the first vibrating screen 2 to generate the primary screening material, and the larger part of the crushed material is screened out and remains above the first vibrating screen 2. The screening efficiency is high, and it is not easy to get clogged, thereby improving the stability and reliability of the operation. In addition, the structure is simple, easy to implement, and low cost.

[0081] In a specific implementation, the mesh number of the first vibrating screen 2 is, for example, not greater than 80 meshes, which has a high screening efficiency for lithium iron phosphate in the crushed material and a good screening effect.

[0082] The mesh size of the first vibrating screen 2 refers to the number of screen holes of the first vibrating screen 2 per inch.

[0083] By setting the mesh number of the first vibrating screen 2 to no more than 80 meshes, that is, the mesh number of the first vibrating screen 2 is smaller, so that under the condition of the same length, the first vibrating screen 2 has fewer sieve holes and a larger aperture, so that the crushed material with the required particle size can pass through the sieve holes more fully to enter the subsequent grinding process, the screening efficiency is high, which facilitates the effective recovery of lithium iron phosphate materials and helps to improve the recovery efficiency of lithium iron phosphate.

[0084] If the mesh number of the first vibrating screen 2 is greater than 80 meshes, that is, the mesh number of the first vibrating screen 2 is larger, then under the condition of the same length, the first vibrating screen 2 has more sieve holes and smaller apertures, and the pass rate of the crushed material is lower. In other words, the screening efficiency of the crushed material is low, which is not conducive to the recovery of lithium iron phosphate materials and affects the recovery efficiency of lithium iron phosphate.

[0085] In other embodiments, for example, an air flow separator may be used to separate metal materials and non-metallic materials such as lithium iron phosphate in the crushed materials by utilizing density differences.

[0086] S103 , grinding the pre-screened material by the grinding equipment 3 to obtain a ground material, wherein the ground material includes metal foil and lithium iron phosphate powder.

[0087] The primary screening material generated in step S102 is ground by the grinding equipment 3. Specifically, the powder generated in step S102 and the fragments and particles with smaller particle size are ground by the grinding equipment 3. On the one hand, the lithium iron phosphate material on the fragments and particles can be fully detached, thereby improving the recovery efficiency of the lithium iron phosphate material. On the other hand, the particle size of the lithium iron phosphate powder and particles is made smaller, further improving the recovery efficiency and recovery effect of the lithium iron phosphate material. Thirdly, the metal materials in the primary screening material, such as metal fragments, can be extended to form metal foil, thereby increasing the particle size difference between the lithium iron phosphate powder and the metal impurities, facilitating the separation of the metal materials and the lithium iron phosphate powder, and realizing the effective recovery of the lithium iron phosphate powder.

[0088] That is, after the grinding equipment 3 grinds the pre-screened material, grinding materials such as metal foil and lithium iron phosphate powder with smaller particle size are obtained.

[0089] In some embodiments, the grinding device 3 may be, for example, a roller press.

[0090] The primary screened material is ground by a roller press, which is sufficient and efficient, and has a simple structure, is easy to implement and has low cost.

[0091] In other embodiments, the grinding device 3 may be, for example, a cyclone mill.

[0092] The following embodiments are explained and illustrated in detail using the grinding device 3 as a roller press.

[0093] S104, sieving the ground material to separate the metal foil and the lithium iron phosphate powder to obtain lithium iron phosphate powder.

[0094] In specific implementation, the grinding material generated in step S103 is screened. On the one hand, powders such as lithium iron phosphate are allowed to pass through the sieve holes, which facilitates the recovery of lithium iron phosphate powder. On the other hand, the metal foil is prevented from passing through the sieve holes and remains above the sieve holes, thereby achieving effective separation of the metal foil and lithium iron phosphate powder, and improving the recovery effect of the lithium iron phosphate powder.

[0095] In some embodiments, the ground material generated in step S103 is screened by a second vibrating screen 4 .

[0096] The grinding material is screened by the second vibrating screen 4. The high-frequency vibration of the second vibrating screen 4 causes the grinding material to vibrate and slide strongly, which can quickly separate the metal foil and the lithium iron phosphate powder, and allow the lithium iron phosphate powder to pass through the sieve holes of the second vibrating screen 4 and be effectively recovered. The metal foil is screened out and remains above the second vibrating screen 4. The screening efficiency is high and it is not easy to get clogged, thereby improving the stability and reliability of the operation. In addition, the structure is simple, the operation is convenient, it is easy to implement, and the cost is low.

[0097] In a specific implementation, the mesh size of the second vibrating screen 4 is 100-120 meshes, which has a high screening efficiency and a good screening effect for the lithium iron phosphate powder in the grinding material.

[0098] The mesh size of the second vibrating screen 4 refers to the number of screen holes of the second vibrating screen 4 per inch.

[0099] By setting the mesh size of the second vibrating screen 4 to 100-120 mesh, the number and aperture of the sieve holes of the second vibrating screen 4 are relatively appropriate under the same length, so that the powder in the grinding material can pass through the sieve holes, and the metal foil can be screened out and left above the second vibrating screen 4, thereby achieving effective recovery of lithium iron phosphate powder, and the recovery purity is high and the recovery effect is good.

[0100] If the mesh number of the second vibrating screen 4 is greater than 120 meshes, that is, the mesh number of the second vibrating screen 4 is larger, then under the condition of the same length, the second vibrating screen 4 has too many sieve holes and the aperture is too small, which causes the sieve holes to be easily blocked by powders such as lithium iron phosphate. In this way, the pass rate of lithium iron phosphate powder is low, affecting the recovery of lithium iron phosphate material.

[0101] If the mesh number of the second vibrating screen 4 is less than 100 meshes, that is, the mesh number of the second vibrating screen 4 is small, then under the condition of the same length, the sieve holes of the second vibrating screen 4 are too few and the aperture is too large, which makes it easy for the metal foil to pass through the sieve holes, resulting in more metal impurities in the recovered lithium iron phosphate powder, affecting the recovery purity of the lithium iron phosphate material.

[0102] Through the above scheme, the method for recovering lithium iron phosphate from battery pole pieces provided in this embodiment first crushes the pole piece to obtain a crushed material, then screens the crushed material to obtain a pre-screened material, and then grinds the pre-screened material through a grinding device 3 to obtain a ground material. Because metals have good ductility, the metal material in the pre-screened material will form metal foil under the grinding action of the grinding device 3. Since lithium iron phosphate is an inorganic compound, the lithium iron phosphate in the pre-screened material will form lithium iron phosphate powder with a smaller particle size under the grinding action of the grinding device 3. In this way, after the grinding device 3 grinds the pre-screened material, a mixture containing metal foil and lithium iron phosphate powder can be obtained. The ground material is then screened to effectively separate the metal foil and lithium iron phosphate powder to obtain lithium iron phosphate powder. Compared with the scheme of mechanically stripping lithium iron phosphate from the pole piece in the prior art, this method avoids the phenomenon of lithium iron phosphate residue on the pole piece to a certain extent, realizes the effective recovery of lithium iron phosphate material, improves the recovery efficiency of lithium iron phosphate, and has a higher recovery purity.

[0103] At the same time, compared with the solution of using a large amount of chemical reagents to recycle lithium iron phosphate materials, it not only reduces the recycling cost, but also avoids the environmental pollution caused by chemical reagents and the corrosion of metal foil by chemical reagents, which is conducive to the subsequent recycling of metals.

[0104] In some embodiments, reference Figure 2 and Figure 3 As shown, the grinding device 3 has a roller structure 9, which is used to grind the pre-screened material to obtain metal foil and lithium iron phosphate powder.

[0105] It should be noted that the material inlet of the grinding equipment 3 for the primary screened material is located above the roller structure 9, so that after the primary screened material enters the grinding equipment 3, it can fall onto the roller structure 9 under the action of gravity, making it easier for the roller structure 9 to grind it.

[0106] By providing the grinding device 3 with a roller structure 9, the structure is simple and easy to implement. The roller structure 9 is used to grind the pre-screened material, so that the metal material in the pre-screened material is formed into metal foil under the grinding action of the roller structure 9, and the lithium iron phosphate particles in the pre-screened material are formed into lithium iron phosphate powder with a smaller particle size under the grinding action of the roller structure 9, thereby separating the lithium iron phosphate from the metal foil, realizing the separation of the lithium iron phosphate from the electrode, and achieving high separation efficiency.

[0107] In some embodiments, reference Figure 3 As shown, the roller structure 9 includes at least one fixed roller 91 and at least two rotating rollers 92. The fixed roller 91 and the rotating rollers 92 are arranged in the horizontal direction. A fixed roller 91 is provided between at least two adjacent rotating rollers 92. The roller gap between adjacent fixed rollers 91 and rotating rollers 92 is 10μm-200μm, and the roller gap between adjacent rotating rollers 92 is 10μm-200μm.

[0108] In specific implementation, the fixed roller 91 and the rotating roller 92 are arranged in the horizontal direction, and a fixed roller is set between at least two adjacent rotating rollers. That is to say, a fixed roller can be set between every two adjacent rotating rollers, that is, the fixed roller and the rotating roller are set at intervals, or a fixed roller can be set between two adjacent rotating rollers.

[0109] The fixed roller 91 is fixed and does not rotate actively, while the rotating roller 92 can rotate actively.

[0110] In specific implementation, the pre-screened material enters the grinding equipment and falls above the roller structure. The pre-screened material then enters the roller gap under the action of the rotating roller 92. As the pre-screened material is forced downward in the roller gap, it is subjected to a gradually increasing extrusion and grinding force, allowing the fragments in the pre-screened material and the lithium iron phosphate material on the particles to fully fall off. The lithium iron phosphate powder and particles are broken into smaller-sized materials that are discharged from the bottom of the roller gap, further improving the recovery efficiency and effect of the lithium iron phosphate material. At the same time, metal materials in the pre-screened material, such as metal fragments, are stretched to form metal foil and discharged from the bottom of the roller gap, increasing the particle size difference between the lithium iron phosphate powder and the metal impurities, facilitating the subsequent separation of the metal materials and the lithium iron phosphate powder, and achieving effective recovery of the lithium iron phosphate powder.

[0111] The roller structure 9 includes at least one fixed roller 91 and at least two rotating rollers 92, the fixed roller 91 and the rotating rollers 92 are arranged in the horizontal direction, and a fixed roller 91 is set between at least two adjacent rotating rollers 92, and the roller gap between the fixed roller 91 and the adjacent rotating roller 92 is 10μm-200μm, and the roller gap between the rotating roller 92 and the adjacent rotating roller 92 is 10μm-200μm. The structure is simple and easy to manufacture. Under the action of the rotating roller 92, the primary screened material is continuously brought into the roller gap and is subjected to a gradually increasing extrusion and grinding force in the process of being forced to move downward, so that the particle size of the lithium iron phosphate powder and the particles is smaller, and the metal material is extended into a larger metal foil, thereby increasing the particle size difference between the lithium iron phosphate powder and the metal foil, having a better grinding effect on the primary screened material, facilitating the grinding and separation of the lithium iron phosphate powder, and helping to improve the separation efficiency and recovery efficiency of the lithium iron phosphate powder.

[0112] In some embodiments, reference Figure 3 As shown, the two rollers of the roller structure 9 located on the outermost side in the horizontal direction are both rotating rollers 92, and when viewed from above in the horizontal direction, the rotation direction of the two rotating rollers 92 located on the outermost side is inward.

[0113] That is to say, the outermost part of the roller structure 9 in its arrangement direction is the rotating roller 92, and when viewed from above in the arrangement direction, the two outermost rotating rollers 92 of the roller structure 9 in its arrangement direction rotate inward, so that after the pre-screened material enters the grinding equipment 3, it can move toward the inner side of the roller structure 9 and can be continuously brought into the roller gap for grinding. To a certain extent, it avoids the accumulation of the pre-screened material on the inner wall of the grinding equipment 3 above the roller structure 9. The reasonable design helps to improve the grinding efficiency and reduce the residue of the pre-screened material in the grinding equipment.

[0114] In some embodiments, the grinding pressure of the rotating roller 92 is 50T-200T.

[0115] By setting the grinding pressure of the rotating roller 92 to 50T-200T, the primary screened material is subjected to a higher roller pressure at the roller gap. Under the action of high pressure, on the one hand, the lithium iron phosphate powder and particles in the primary screened material are broken to form materials with smaller particle sizes. On the other hand, the metal materials in the primary screened material, such as metal fragments, are stretched and deformed into larger metal foils, further improving the grinding efficiency of the roller structure 9.

[0116] In some embodiments, the rotation speed of the rotating roller 92 is 1 m / s-5 m / s.

[0117] If the rotation speed of the rotating roller 92 is too low, the pre-screened material stays in the roller gap for too long, which will block the roller gap and affect the normal operation of the grinding equipment.

[0118] If the rotation speed of the rotating roller 92 is too high, the pre-screened material will be discharged from the bottom of the roller gap relatively quickly under the drive of the rotating roller 92. In this way, the pre-screened material is squeezed and ground in the roller gap for too short a time, and the grinding is insufficient.

[0119] By setting the rotation speed of the rotating roller 92 to 1m / s-5m / s, the number of times the primary screened material is ground per unit time is increased while ensuring the same residence contact time of the primary screened material at the roller gap, thereby improving the grinding efficiency and making the recovery efficiency of the lithium iron phosphate powder higher.

[0120] In some embodiments, reference Figure 2 and Figure 3 As shown, the roller structure 9 has at least two stages, and at least two stages of roller structures 9 are arranged in sequence along the vertical direction, and the roller gaps of adjacent two stages of roller structures 9 are staggered in the vertical direction.

[0121] In other words, the roller gap of the upper roller structure 9 and the roller gap of the lower roller structure 9 will not overlap after extending in the vertical direction, so that the positive projection of the roller gap of the upper roller structure 9 is located on the fixed roller 91 or the rotating roller 92 of the lower roller structure 9. With this arrangement, the grinding material will not directly enter the roller gap of the lower roller structure 9 after falling from the roller gap of the upper roller structure 9, which increases the contact time between the grinding material and the roller structure 9, thereby improving the grinding efficiency and further improving the recovery rate of the lithium iron phosphate powder.

[0122] In some embodiments, the grinding pressure of the grinding device 3 is 50T-200T.

[0123] In some embodiments, the grinding equipment 3 performs at least two-stage grinding processes on the pre-screened material.

[0124] The primary screened material is subjected to at least two-stage grinding processing by the grinding equipment 3, so that the primary screened material will be ground and processed at least twice after entering the grinding equipment 3, that is, the ground material generated by the previous stage of grinding will enter the next stage to continue to be ground and processed, which increases the grinding processing time of the primary screened material, thereby improving the grinding efficiency, and further improving the recovery rate of the lithium iron phosphate powder.

[0125] In some embodiments, reference Figure 2 and Figure 4 As shown, the method for recovering lithium iron phosphate from battery pole pieces also includes:

[0126] S105 , conveying the lithium iron phosphate powder to the storage bin 6 through the first conveying line 7 .

[0127] By providing the storage bin 6 and conveying the lithium iron phosphate powder obtained by sieving the ground material to the storage bin 6 via the first conveyor line 7, the lithium iron phosphate powder is automatically recovered and stored, thereby improving the degree of automation of lithium iron phosphate powder recovery, making recovery more convenient and facilitating subsequent use.

[0128] In some embodiments, reference Figure 2 As shown, at least one fool-proof structure 5 is provided on the first conveyor line 7, and the fool-proof structure 5 is electrically connected to the first conveyor line 7. The fool-proof structure 5 is used to detect metal foreign matter in the lithium iron phosphate powder. The first conveyor line 7 is used to stop when the fool-proof structure 5 detects metal foreign matter in the lithium iron phosphate powder.

[0129] By arranging an anti-foolproof structure 5 on the first conveyor line 7, the lithium iron phosphate powder is detected by the anti-foolproof structure 5, and the first conveyor line 7 can stop conveying the lithium iron phosphate powder into the storage bin 6 when the anti-foolproof structure 5 detects metal foreign matter in the lithium iron phosphate powder. The degree of automation is high, the use is convenient, and the recovery efficiency of the lithium iron phosphate powder is guaranteed to a certain extent.

[0130] In some implementations, a plurality of fool-proof structures 5 are provided on the first conveyor line 7, and the plurality of fool-proof structures 5 are spaced apart along the length direction of the first conveyor line 7. With such a configuration, the detection effect of metal foreign matter in the lithium iron phosphate powder is better, and the recovery purity of the lithium iron phosphate powder is further improved.

[0131] For example, refer to Figure 2 As shown, three fool-proof structures 5 are arranged at intervals along the length direction of the first conveyor line 7.

[0132] In specific implementation, the fool-proof structure 5 can be, for example, a cleanliness analyzer.

[0133] The cleanliness analyzer can, for example, analyze the cleanliness of the lithium iron phosphate powder by irradiating the lithium iron phosphate powder on the first conveyor line 7 with a light source and measuring whether the lithium iron phosphate powder reflects light.

[0134] Lithium iron phosphate powder is an inorganic compound, typically gray or black. Its appearance means it doesn't reflect light like metal, so it doesn't reflect light when passing through a cleanliness analyzer. However, when metallic foreign matter is exposed to light, its surface smoothness and metallic gloss reflect light, resulting in a reflective effect. Therefore, light reflection can be used to identify metallic foreign matter. Therefore, the cleanliness analyzer can detect light when metallic foreign matter passes through it.

[0135] In specific implementation, the cleanliness analyzer performs detection by irradiating the lithium iron phosphate powder on the first conveyor line 7 with a light source.

[0136] If there is no metal foreign matter in the lithium iron phosphate powder, the cleanliness analyzer will not collect reflected light when the lithium iron phosphate powder passes through the cleanliness analyzer, and it is considered that there is no metal foreign matter in the lithium iron phosphate powder passing through the cleanliness analyzer.

[0137] If the lithium iron phosphate powder is mixed with metal foreign matter, the cleanliness analyzer can collect reflected light when the lithium iron phosphate powder passes through the cleanliness analyzer, and it is considered that the lithium iron phosphate powder passing through the cleanliness analyzer is mixed with metal foreign matter. At the same time, the first conveyor line 7 stops working, so as to ensure that the lithium iron phosphate powder mixed with metal foreign matter will not enter the storage bin 6, thereby improving the recovery quality of the lithium iron phosphate powder.

[0138] In some embodiments, reference Figure 2 and Figure 4 As shown, the method for recovering lithium iron phosphate from battery pole pieces also includes:

[0139] When the foolproof structure 5 detects metal foreign matter in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line 7 is returned to the grinding device 3 through the second conveyor line 8 to be ground again.

[0140] In specific implementation, when the fool-proof structure 5 detects that there are metal foreign objects in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line 7 can be returned to the grinding equipment 3 through the second conveyor line 8, so that the grinding equipment 3 can continue to grind the returned lithium iron phosphate powder, further improving the degree of automation of lithium iron phosphate powder recovery and the recovery efficiency of lithium iron phosphate powder, and ensuring the recovery quality of lithium iron phosphate powder.

[0141] Of course, the lithium iron phosphate powder discharged from the roller press outlet can also be directly conveyed to the roller press via the second conveyor line 8 for re-grinding to improve the recovery quality and recovery efficiency of the lithium iron phosphate powder.

[0142] In some embodiments, the method for recovering lithium iron phosphate from battery electrodes further comprises:

[0143] S106 , performing an element test (Inductively Coupled Plasma, hereinafter referred to as ICP test) on the lithium iron phosphate powder in the storage bin 6 , and adjusting the operating parameters of the grinding device 3 when the aluminum content is greater than a first preset threshold and / or the copper content is greater than a second preset threshold.

[0144] By performing an ICP test on the lithium iron phosphate powder in the storage bin 6, it is determined whether the aluminum content is greater than the first preset threshold and / or whether the copper content is greater than the second preset threshold. That is, by detecting whether the aluminum content and copper content in the recovered lithium iron phosphate powder meet the standards, the working parameters of the grinding equipment 3 are adjusted, thereby further improving the recovery purity and recovery efficiency of the lithium iron phosphate.

[0145] The first preset threshold refers to the maximum value of the aluminum content of the sampled lithium iron phosphate powder within a preset recovery purity range. In other words, if the aluminum content is greater than the first preset threshold, it indicates that the recovery purity of the lithium iron phosphate powder is low. If the aluminum content is less than the first preset threshold, it indicates that the recovery purity of the lithium iron phosphate powder is high.

[0146] The second preset threshold value refers to the maximum value of the copper content in the sampled lithium iron phosphate powder within the preset recovery purity range. In other words, if the copper content is greater than the first preset threshold value, it indicates that the recovery purity of the lithium iron phosphate powder is low. If the copper content is less than the first preset threshold value, it indicates that the recovery purity of the lithium iron phosphate powder is high. This refers to the critical value of the copper content in the lithium iron phosphate powder.

[0147] The operating parameters of the grinding device 3 may include, for example, the pressure of the roller press, the size of the roller gap, the rotation speed of the rotating roller 92 , and the like.

[0148] In specific implementation, for example, a certain weight of lithium iron phosphate powder sample can be taken out from the storage bin 6 and an ICP test can be performed to measure whether the aluminum content and the copper content meet the standards.

[0149] Of course, the lithium iron phosphate powder in the storage bin 6 may also be subjected to processing performance tests, electrical performance tests, and the like.

[0150] In summary, the waste lithium iron phosphate pole piece is fed into the crushing structure 1 for crushing to obtain a crushed material. The crushed material is screened through the first vibrating screen 2 to obtain a pre-screened material. The pre-screened material is then fed into a roller press for grinding to obtain a ground material, wherein the ground material includes metal foil and lithium iron phosphate powder. The ground material is then screened through the second vibrating screen 4 to obtain the lithium iron phosphate powder to be recycled. Compared with the solution of mechanically peeling lithium iron phosphate from the pole piece in the prior art, this method avoids the occurrence of residual lithium iron phosphate on the pole piece to a certain extent, realizes the effective recovery of lithium iron phosphate materials, improves the recovery efficiency of lithium iron phosphate, and has a higher recovery purity.

[0151] At the same time, compared with the solution of using a large amount of chemical reagents to recycle lithium iron phosphate materials, it not only reduces the recycling cost, but also avoids the environmental pollution caused by chemical reagents and the corrosion of metal foil by chemical reagents, which is conducive to the subsequent recycling of metals.

[0152] Furthermore, the outlet of the roller press is connected to the storage bin 6 via a first conveyor line 7, and a fool-proof structure 5 is provided on the first conveyor line 7 to detect the lithium iron phosphate powder on the first conveyor line 7. When the fool-proof structure 5 does not sound an alarm, the lithium iron phosphate powder on the first conveyor line 7 is conveyed to the storage bin 6. When the fool-proof structure 5 sounds an alarm, the lithium iron phosphate powder on the first conveyor line 7 is conveyed to the storage bin 6 via a second conveyor line 8 to the roller press for further grinding. In other words, the lithium iron phosphate powder can only enter the storage bin 6 for storage via the first conveyor line 7 when the fool-proof structure 5 does not sound an alarm, thereby ensuring the recovery efficiency and quality of the lithium iron phosphate powder.

[0153] In addition, by performing an ICP test on the lithium iron phosphate powder in the storage bin 6 and adjusting the working performance of the roller press according to the aluminum content and copper content obtained from the ICP test, the recovery efficiency and quality of the lithium iron phosphate powder can be further guaranteed.

[0154] In other words, through the crushing, grinding, and screening processes, lithium iron phosphate can be effectively separated from the waste lithium iron phosphate electrode sheets, improving recycling efficiency. At the same time, the foolproof structure 5 on the first conveyor line 7 prevents metallic foreign matter from entering the storage bin 6, ensuring the recovery quality of the lithium iron phosphate powder. Furthermore, combined with ICP testing of the lithium iron phosphate powder in the storage bin 6, the operating parameters of the roller press can be adjusted, further ensuring the recovery efficiency and quality of the lithium iron phosphate powder.

[0155] At the same time, compared with the solution of using a large amount of chemical reagents to recover lithium iron phosphate, the recovery cost is reduced and the environmental pollution caused by chemical reagents is avoided.

[0156] refer to Figure 2 and Figure 3 As shown, this embodiment also provides a lithium iron phosphate recovery device. The above-mentioned method for recovering lithium iron phosphate from battery pole pieces can be carried out using the lithium iron phosphate recovery device to achieve effective recovery of lithium iron phosphate from waste lithium iron phosphate pole pieces, with relatively high recovery efficiency and recovery purity.

[0157] At the same time, the physical recovery of lithium iron phosphate is achieved without the use of chemical reagents, avoiding the environmental pollution caused by the use of chemical reagents, and preventing secondary pollution, thereby reducing subsequent processing costs and, to a certain extent, the recycling cost of lithium iron phosphate. In addition, it also avoids the corrosion of metal foil caused by the use of chemical reagents, improving the quality of metal recovery.

[0158] Specifically, refer to Figure 2 As shown, the lithium iron phosphate recovery device includes a crushing structure 1, a first vibrating screen 2, a grinding device 3 and a second vibrating screen 4.

[0159] The crushing structure 1 is used to crush the waste lithium iron phosphate electrodes to obtain crushed materials; the inlet of the first vibrating screen 2 is connected to the outlet of the crushing structure 1, and the first vibrating screen 2 is used to screen the crushed materials to obtain pre-screened materials; the feed port of the grinding equipment 3 is connected to the outlet of the first vibrating screen 2, and the grinding equipment 3 is used to grind the pre-screened materials screened by the first vibrating screen 2; the inlet of the second vibrating screen 4 is connected to the discharge port of the grinding equipment 3, and the second vibrating screen 4 is used to screen the ground materials discharged through the discharge port of the grinding equipment 3 to obtain lithium iron phosphate powder.

[0160] In the specific implementation, first, the waste lithium iron phosphate electrode is placed in the crushing structure 1, and the crushing structure 1 is started. The crushing structure 1 can crush it, thereby crushing the waste lithium iron phosphate electrode into crushed materials, which include powder, fine fragments, fine particles, etc.

[0161] The lithium iron phosphate electrode is crushed by the crushing structure 1, so that the lithium iron phosphate and other non-metallic materials on the lithium iron phosphate electrode fall off from the metal foil to a certain extent, which facilitates the subsequent separation of the lithium iron phosphate and other non-metallic materials from the metal impurities.

[0162] Secondly, the crushed material formed by the crushing structure 1 is placed in the first vibrating screen 2 for screening to obtain the primary screened material. Screening the crushed material allows the smaller parts of the crushed material to pass through the sieve holes, such as powder, small-sized fragments and particles, to form the primary screened material and enter the subsequent steps to facilitate the recovery of lithium iron phosphate. The larger parts of the crushed material, such as large-sized fragments and particles, are screened out to prevent the larger parts of the crushed material from flowing into the subsequent steps and affecting the subsequent grinding efficiency. This achieves the effect of screening and separating large particles from the crushed material, which helps to improve the recovery efficiency of lithium iron phosphate.

[0163] The first vibrating screen 2 is used to vibrate and screen the crushed material. The high-frequency vibration of the first vibrating screen 2 causes the crushed material to vibrate and slide strongly, which can quickly separate crushed materials of different particle sizes, allowing the smaller parts of the crushed material to pass through the sieve holes of the first vibrating screen to generate primary screening materials, and allowing the larger parts of the crushed material to be screened out and remain above the first vibrating screen. The screening efficiency is high, and it is not easy to get clogged, thereby improving the stability and reliability of operation. In addition, the structure is simple, easy to implement, and low cost.

[0164] In some implementations, for example, the larger portion of the pulverized material that has been screened out can be added back into the pulverizing structure 1 for secondary pulverization. This not only avoids the waste of materials caused by incomplete pulverization of lithium iron phosphate electrodes to a certain extent, but also improves the recovery efficiency of lithium iron phosphate to a certain extent.

[0165] Then, the pre-screened material obtained by screening the first vibrating screen 2 is placed in the grinding device 3 and ground by the grinding device 3 to obtain a ground material, wherein the ground material includes metal foil and lithium iron phosphate powder.

[0166] In specific implementation, the grinding equipment 3 grinds the powder screened by the first vibrating screen 2 and the fragments and particles with smaller particle sizes. On the one hand, the lithium iron phosphate material on the fragments and particles can be fully shed, thereby improving the recovery efficiency of the lithium iron phosphate material. On the other hand, the particle size of the lithium iron phosphate powder and particles is made smaller, further improving the recovery efficiency and recovery effect of the lithium iron phosphate material. Thirdly, the metal materials in the primary screening material, such as metal fragments, can be extended to form metal foil, thereby increasing the particle size difference between the lithium iron phosphate powder and the metal impurities, facilitating the separation of the metal materials and the lithium iron phosphate powder, and realizing the effective recovery of the lithium iron phosphate powder.

[0167] That is, after the grinding equipment 3 grinds the pre-screened material, grinding materials such as metal foil and lithium iron phosphate powder with smaller particle size are obtained.

[0168] Finally, the ground material generated by the grinding device 3 is placed in the second vibrating screen 4 for sieving, and the lithium iron phosphate powder to be recycled can be obtained.

[0169] The grinding material is screened. On the one hand, it allows powders such as lithium iron phosphate to pass through the sieve holes, making it easier to recover the lithium iron phosphate powder. On the other hand, it prevents metal foil from passing through the sieve holes and leaves it above the sieve holes, thereby achieving effective separation of the metal foil and lithium iron phosphate powder and improving the recovery effect of the lithium iron phosphate powder.

[0170] The grinding material is screened by the second vibrating screen 4. The high-frequency vibration of the second vibrating screen 4 causes the grinding material to vibrate and slide strongly, which can quickly separate the metal foil and the lithium iron phosphate powder, and allow the lithium iron phosphate powder to pass through the sieve holes of the second vibrating screen and be effectively recovered. The metal foil is screened out and remains above the second vibrating screen, with high screening efficiency and not easy to clog, thereby improving the stability and reliability of operation. In addition, the structure is simple, the operation is convenient, it is easy to implement, and the cost is low.

[0171] For specific implementation, refer to Figure 2 As shown, the outlet of the crushing structure 1 can be directly connected to the inlet of the first vibrating screen 2. Of course, in other implementations, the outlet of the crushing structure 1 can also be connected to the inlet of the first vibrating screen 2, for example, through a pipeline, a conveying line, etc.

[0172] Similarly, the outlet of the first vibrating screen 2 can be connected to the feed port of the grinding device 3 directly or through a pipeline, a conveyor line, etc. The discharge port of the grinding device 3 can be connected to the inlet of the second vibrating screen 4 directly or through a pipeline, a conveyor line, etc.

[0173] The lithium iron phosphate recovery device provided in the present application is provided with a crushing structure 1, a first vibrating screen 2, a grinding device 3 and a second vibrating screen 4, so that the outlet of the crushing structure 1 is connected to the inlet of the first vibrating screen 2, the outlet of the first vibrating screen 2 is connected to the feed port of the grinding device 3, and the discharge port of the grinding device 3 is connected to the inlet of the second vibrating screen 4, that is, the crushing structure 1, the first vibrating screen 2, the grinding device 3 and the second vibrating screen 4 are connected in sequence. When used specifically, the lithium iron phosphate pole pieces in the waste lithium iron phosphate battery are first crushed by the crushing structure 1 to obtain crushed material, and then the crushed material is screened by the first vibrating screen 2 to obtain pre-screened material, and then the pre-screened material is ground by the grinding device 3 to obtain ground material. Since metals have good ductility, if there is metal material in the primary screening material, the metal material will be extended to form metal foil under the grinding action of the grinding device 3. Since lithium iron phosphate is an inorganic compound, the lithium iron phosphate in the primary screening material will form lithium iron phosphate powder with a smaller particle size under the grinding action of the grinding device 3. In this way, after the primary screening material is ground by the grinding device 3, a mixture containing metal foil and lithium iron phosphate powder can be obtained. Finally, the ground material is screened through the second vibrating screen 4, and the metal foil and lithium iron phosphate powder can be effectively separated to obtain the lithium iron phosphate powder to be recycled. Compared with the solution using chemical reagent leaching process in the related art, no chemical reagent is required, and the physical recovery of lithium iron phosphate is achieved, thereby avoiding the environmental pollution caused by the use of chemical reagents, and will not cause secondary pollution, reducing the subsequent processing costs, and thus reducing the recovery cost of lithium iron phosphate to a certain extent. At the same time, it also avoids the corrosion of metal foil by chemical reagents, improving the recovery quality of metal.

[0174] In addition, compared with the solution of mechanically stripping lithium iron phosphate from the electrode in the prior art, this method avoids the occurrence of lithium iron phosphate residue on the electrode to a certain extent, realizes the effective recovery of lithium iron phosphate, and improves the recovery efficiency and purity of lithium iron phosphate.

[0175] In some embodiments, reference Figures 1 to 5 As shown, the grinding device 3 includes a hollow first shell and a roller structure 9. The first shell is provided with a feed port and a discharge port, both of which are connected to the hollow cavity of the first shell. The roller structure 9 is disposed within the first shell and located between the feed port and the discharge port. The roller structure 9 is used to grind the pre-screened material.

[0176] That is to say, the grinding equipment 3 includes a first shell and a roller structure 9. The first shell is a hollow structure, and the first shell is provided with a feed port and a discharge port connected to the cavity therein. The roller structure 9 is arranged in the first shell and is located between the feed port and the discharge port. In this way, the primary screened material obtained by screening the first vibrating screen 2 enters the first shell through the feed port, and will be ground by the roller structure 9. After being ground by the roller structure 9, the formed ground material can be discharged from the discharge port under the action of gravity. The structure is simple, easy to implement, convenient to use, and helps to improve work efficiency.

[0177] At the same time, the roller structure 9 is used to grind the primary screened material, so that the metal material in the primary screened material is extended to form metal foil under the grinding action of the roller structure 9, and the lithium iron phosphate in the primary screened material is formed into lithium iron phosphate powder with smaller particle size under the grinding action of the roller structure 9, thereby separating the lithium iron phosphate from the metal foil, realizing the separation of lithium iron phosphate from the electrode, and the separation efficiency is high.

[0178] In some embodiments, reference Figure 1 、 Figures 3 to 5 As shown, the feed port can be set at the top of the first shell, so that after the pre-screened material enters the first shell through the feed port, it can fall onto the roller structure 9 under the action of gravity and be ground, which is convenient for the roller structure 9 to grind it, saves energy, is easy to use, and helps to improve the efficiency of the grinding process.

[0179] Of course, the feed port can be provided on the side of the first shell, for example.

[0180] In some embodiments, reference Figure 1 、 Figures 3 to 5 As shown, the discharge port is arranged at the bottom of the first shell, so that the ground material formed by the grinding process of the roller structure 9 can be discharged under the action of gravity, which saves energy consumption, is easy to use, and helps to improve the efficiency of the grinding process.

[0181] Of course, the discharge port may also be provided on the side of the first shell, for example.

[0182] In some embodiments, reference Figure 1 、 Figures 3 to 5 As shown, in the direction from the feed port to the discharge port (reference Figure 2 In the X direction), the inner cavity size of at least part of the first shell gradually decreases.

[0183] That is to say, the inner cavity of the first shell decreases in the direction from the feed port to the discharge port, so that the inner cavity of the first shell is larger on the feed port side and smaller on the discharge port side, thereby facilitating the timely discharge of the ground material into the downstream process and being easy to use.

[0184] By way of example, the grinding device 3 may be, for example, a roller press.

[0185] In other implementations, the grinding device 3 may be, for example, a cyclone mill.

[0186] In some embodiments, reference Figures 1 to 5 As shown, the roller structure 9 includes at least one fixed roller 91 and at least two rotating rollers 92; the fixed rollers 91 and the rotating rollers 92 are arranged in a horizontal direction, and a fixed roller 91 is provided between at least two adjacent rotating rollers 92, and the roller gaps between adjacent fixed rollers 91 and rotating rollers 92 and the roller gaps between two adjacent rotating rollers 92 are not greater than a first preset value.

[0187] In specific implementation, the fixed roller 91 and the rotating roller 92 are arranged in the horizontal direction, and a fixed roller 91 is set between at least two adjacent rotating rollers 92. That is to say, a fixed roller 91 can be set between every two adjacent rotating rollers 92, that is, the fixed roller 91 and the rotating roller 92 are set at intervals, or a fixed roller 91 can be set between two adjacent rotating rollers 92, that is, there is a situation where no fixed roller is set between the two rotating rollers.

[0188] The fixed roller 91 is fixed and does not actively rotate, while the rotating roller 92 can actively rotate, for example, by being driven by a motor.

[0189] In specific implementation, the pre-screened material enters the grinding device 3 and falls above the roller structure 9. The pre-screened material then enters the roller gap under the action of the rotating roller 92. In the process of being forced to move downward in the roller gap, the pre-screened material is subjected to a gradually increasing extrusion and grinding force, which allows the fragments in the pre-screened material and the lithium iron phosphate material on the particles to fully fall off, and causes the lithium iron phosphate powder and particles to break into smaller particles and be discharged from the bottom of the roller gap, further improving the recovery efficiency and recovery effect of the lithium iron phosphate material. At the same time, the metal materials in the pre-screened material, such as metal fragments, are extended to form metal foil and discharged from the bottom of the roller gap, increasing the particle size difference between the lithium iron phosphate powder and the metal impurities, facilitating the subsequent separation of the metal materials and the lithium iron phosphate powder, and realizing the effective recovery of the lithium iron phosphate powder.

[0190] By making the roller structure 9 include at least one fixed roller 91 and at least two rotating rollers 92, the fixed roller 91 and the rotating rollers 92 are arranged in the horizontal direction, and a fixed roller 91 is set between at least two adjacent rotating rollers 92, and the roller gap between the fixed roller 91 and its adjacent rotating roller 92 is not greater than the first preset value, and the roller gap between the rotating roller 92 and its adjacent rotating roller 92 is not greater than the first preset value. The structure is simple and easy to manufacture, and under the action of the rotating roller 92, the primary screened material is continuously brought into the roller gap, and is subjected to a gradually increasing extrusion and grinding force in the process of being forced to move downward, so that the particle size of the lithium iron phosphate powder and the particles is smaller, and the metal material is extended into a larger metal foil, thereby increasing the particle size difference between the lithium iron phosphate powder and the metal foil, having a better grinding effect on the primary screened material, facilitating the grinding and separation of the lithium iron phosphate powder, and helping to improve the separation efficiency and recovery efficiency of the lithium iron phosphate powder.

[0191] In some embodiments, the first preset value may be, for example, 10 μm-200 μm.

[0192] By setting the roller gap to 10μm-200μm, the extrusion and grinding force on the primary screened material when passing through the roller gap is greater, the primary screened material is ground for an appropriate time at the roller gap, and the grinding effect on the primary screened material is better. Not only can the particle size of the lithium iron phosphate powder in the primary screened material be smaller, but the metal material can also be stretched to form a larger metal foil, further increasing the particle size difference between the lithium iron phosphate powder and the metal foil, the grinding effect on the primary screened material is better, and the grinding and separation of the lithium iron phosphate powder is facilitated, thereby making the separation efficiency and recovery efficiency of the lithium iron phosphate powder higher.

[0193] In some embodiments, reference Figures 1 to 5 As shown, the two rollers of the roller structure 9 located on the outermost side in the horizontal direction are both rotating rollers 92, and when viewed from above in the horizontal direction, the rotation direction of the two rotating rollers 92 located on the outermost side is inward.

[0194] That is to say, the outermost part of the roller structure 9 in its arrangement direction is the rotating roller 92, and when viewed from above in the arrangement direction, the two outermost rotating rollers 92 of the roller structure 9 in its arrangement direction rotate inward, so that after the pre-screened material enters the grinding equipment 3, it can move toward the inner side of the roller structure 9 and can be continuously brought into the roller gap for grinding. To a certain extent, it avoids the accumulation of the pre-screened material on the inner wall of the grinding equipment 3 above the roller structure 9. The reasonable design helps to improve the grinding efficiency and reduce the residue of the pre-screened material in the grinding equipment 3.

[0195] In some embodiments, the gap between the two outermost rollers of the roller structure 9 in the horizontal direction and the inner wall of the first shell is no greater than a second preset value.

[0196] That is to say, the gap between the outer contour of the roller structure 9 in its arrangement direction and the inner wall of the first shell is not greater than the second preset value, which can prevent the primary screened material from escaping from between the roller structure 9 and the inner wall of the first shell, so that the primary screened material can move toward the inner side of the roller structure 9 to be ground and processed, thereby improving the grinding efficiency and thus improving the recovery efficiency of lithium iron phosphate.

[0197] In specific implementation, the second preset value may be, for example, 2 μm-5 μm, which can avoid interference with the inner wall of the first shell and effectively prevent the primary screened material from escaping.

[0198] In some embodiments, at least one axial end of the rotating roller 92 is rotatably connected to the inner wall of the first shell.

[0199] By rotatably connecting the end of the rotating roller 92 to the inner wall of the first shell, the rotating roller 92 can be directly assembled on the first shell, so that the size between the axial end of the rotating roller 92 and the inner wall of the first shell is relatively small, thereby preventing the primary screened material from escaping from between the axial end of the roller structure 9 and the inner wall of the first shell, thereby improving the grinding efficiency and further improving the recovery efficiency of lithium iron phosphate.

[0200] In other embodiments, the rotating roller 92 may be connected to a bracket, for example, and the bracket is fixed to the inner wall of the first shell.

[0201] In some embodiments, the grinding pressure of the rotating roller 92 is 50T-200T.

[0202] By setting the grinding pressure of the rotating roller 92 to 50T-200T, the primary screened material is subjected to a higher roller pressure at the roller gap. Under the action of high pressure, on the one hand, the lithium iron phosphate powder and particles in the primary screened material are broken to form materials with smaller particle sizes. On the other hand, the metal materials in the primary screened material, such as metal fragments, are stretched and deformed into larger metal foils, further improving the grinding efficiency of the roller structure 9.

[0203] In some embodiments, the rotation speed of the rotating roller 92 is 1 m / s-5 m / s.

[0204] If the rotation speed of the rotating roller 92 is too low, the pre-screened material stays in the roller gap for too long, which will block the roller gap and affect the normal operation of the grinding equipment 3.

[0205] If the rotation speed of the rotating roller 92 is too high, the pre-screened material will be discharged from the bottom of the roller gap relatively quickly under the drive of the rotating roller 92. In this way, the pre-screened material is squeezed and ground in the roller gap for too short a time, and the grinding is insufficient.

[0206] Therefore, by setting the rotation speed of the rotating roller 92 to 1m / s-5m / s, while ensuring that the contact time of the primary screened material at the roller gap is the same, the number of times the primary screened material is ground per unit time is increased, thereby improving the grinding efficiency, and further making the recovery efficiency of lithium iron phosphate powder higher.

[0207] In some embodiments, reference Figures 1 to 5 As shown, the roller structure 9 has at least two stages, and at least two stages of roller structures 9 are arranged in sequence along the vertical direction, and the roller gaps of adjacent two stages of roller structures 9 are staggered in the vertical direction.

[0208] In other words, the roller gap of the upper roller structure 9 and the roller gap of the lower roller structure 9 will not overlap in the vertical direction, so that the positive projection of the roller gap of the upper roller structure 9 is located on the fixed roller 91 or the rotating roller 92 of the lower roller structure 9. With this arrangement, the grinding material will not directly enter the roller gap of the lower roller structure 9 after falling from the roller gap of the upper roller structure 9, which increases the contact time between the grinding material and the roller structure 9, thereby improving the grinding efficiency and further improving the recovery rate of the lithium iron phosphate powder.

[0209] By making the roller structure 9 at least two-stage, the grinding equipment 3 can perform at least two-stage grinding processing on the primary screened material, so that the primary screened material will be ground and processed at least twice after entering the grinding equipment 3, that is, the ground material generated by the previous stage of grinding will enter the next stage to continue to be ground and processed, which increases the grinding processing time of the primary screened material, thereby improving the grinding efficiency, and further improving the recovery rate of the lithium iron phosphate powder.

[0210] In some embodiments, reference Figure 1 、 Figures 3 to 5 As shown, the pulverizing structure 1 includes a hollow second shell and a pulverizing assembly; the second shell has an openable and closable inlet and outlet, and the pulverizing assembly is arranged in the second shell and can rotate relative to the second shell.

[0211] By making the pulverizing structure 1 include a second shell and a pulverizing assembly, the second shell is a hollow structure, and the second shell has an inlet and an outlet connected to the cavity therein, and the inlet and outlet of the second shell can be opened and closed, and the pulverizing assembly is arranged in the second shell. In this way, after the lithium iron phosphate electrode is placed in the second shell, the inlet of the second shell is closed. In this way, the pulverizing assembly can also pulverize the lithium iron phosphate electrode in a relatively sealed environment. On the one hand, foreign matter is prevented from entering the second shell and contaminating the pulverized material obtained by the pulverization process, thereby improving the purity of the subsequent lithium iron phosphate powder. On the other hand, the leakage of the pulverized material obtained by the pulverization process is prevented, thereby improving the recovery rate of the lithium iron phosphate powder.

[0212] In a specific implementation, the inlet of the second shell can be set at its top, and the outlet of the second shell can be set at its bottom, so as to facilitate the placement of lithium iron phosphate electrodes and the discharge of crushed materials, which helps to improve work efficiency.

[0213] In some embodiments, reference Figure 1 、 Figures 3 to 5 As shown, the crushing assembly includes a driving member (not shown), a connecting rod 11, and a plurality of blades 12. The plurality of blades 12 are arranged at least at one end of the connecting rod 11 at intervals along the circumference of the connecting rod 11. The other end of the connecting rod 11 is connected to the driving member, which is used to drive the connecting rod 11 to rotate relative to the second housing, thereby driving the plurality of blades 12 to rotate and crush the lithium iron phosphate electrode.

[0214] During specific use, the connecting rod 11 is driven to rotate by a driving member, and the connecting rod 11 drives the blades 12 to rotate when the connecting rod 11 rotates. The rotation of the blades 12 can crush the lithium iron phosphate electrode. The structure is simple, easy to manufacture, and easy to use.

[0215] In specific implementation, part of the blades 12 can be set at the bottom end of the connecting rod 11 along the circumference of the connecting rod 11, and part of the blades 12 can be set at one side of the bottom end of the connecting rod 11 along the axial direction of the connecting rod 11, which has a higher efficiency in crushing the lithium iron phosphate electrode.

[0216] In some implementations, each blade 12 can be directly connected to the connecting rod 11, which is flexible. If a blade 12 is damaged, only the damaged blade 12 needs to be replaced, which saves costs.

[0217] In other implementations, all blades 12 may be, for example, integral structures for ease of assembly.

[0218] In some embodiments, reference Figure 1 、 Figures 3 to 5 As shown, along the side away from the first vibration screen 2 to the side close to the first vibration screen 2 (reference Figure 2 In the X direction), the inner cavity size of at least part of the second shell gradually decreases.

[0219] By reducing the inner cavity of the second shell in the direction from the side away from the first vibrating screen 2 to the side close to the first vibrating screen 2, that is, the inner cavity of the second shell is larger on the side away from the first vibrating screen 2, and the inner cavity of the first shell is smaller on the side close to the first vibrating screen 2, that is, the inner cavity of the second shell is larger on the inlet side and smaller on the outlet side, it is convenient to discharge the crushed material into the downstream process in time, and it is easy to use.

[0220] For example, the crushing structure 1 may be a crusher, which has a simple structure, is easy to implement, has low cost, and has a good crushing effect.

[0221] In other embodiments, the crushing structure 1 may be, for example, an angle grinder, a double-shaft shredder, etc.

[0222] In some embodiments, the mesh size of the first vibrating screen 2 is not greater than 80 meshes, which has a high screening efficiency and a good screening effect for lithium iron phosphate in the crushed material.

[0223] The mesh number of the first vibrating screen 2 refers to the number of screen holes in the first vibrating screen per inch.

[0224] At the same time, the mesh number of the first vibrating screen 2 is set to no more than 80 meshes, that is, the mesh number of the first vibrating screen 2 is smaller. In this way, under the condition of the same length, the first vibrating screen has fewer sieve holes and a larger aperture, so that the crushed material with the required particle size can pass through the sieve holes more fully to enter the subsequent grinding process. The screening efficiency is high, which facilitates the effective recovery of lithium iron phosphate materials and helps to improve the recovery efficiency of lithium iron phosphate.

[0225] In other embodiments, for example, the pulverized material may be screened by an airflow separator, which utilizes density differences to separate metal materials and non-metallic materials such as lithium iron phosphate in the pulverized material.

[0226] In some embodiments, the mesh size of the second vibrating screen 4 is 100-120 meshes, which has a high screening efficiency and a good screening effect for the lithium iron phosphate powder in the grinding material.

[0227] The mesh number of the second vibrating screen 4 refers to the number of screen holes of the second vibrating screen per inch.

[0228] By setting the mesh size of the second vibrating screen 4 to 100-120 mesh, the number and aperture of the screen holes of the second vibrating screen are more appropriate when the length is the same, so that the powder in the grinding material can pass through the screen holes, and the metal foil can be screened out and left above the second vibrating screen, thereby achieving effective recovery of lithium iron phosphate powder, and the recovery purity is higher and the recovery effect is better.

[0229] In other embodiments, for example, the ground material may be screened using an airflow separator, which uses density differences to separate metal materials from non-metallic materials such as lithium iron phosphate in the ground material.

[0230] In some embodiments, reference Figure 3 and Figure 5As shown, the lithium iron phosphate recovery device further includes a first conveying line 7 and a storage bin 6. One end of the first conveying line 7 is connected to the outlet of the second vibrating screen 4, and the other end of the first conveying line 7 is connected to the storage bin 6.

[0231] That is to say, the inlet of the first conveyor line 7 is connected with the outlet of the second vibrating screen 4, and the outlet of the first conveyor line 7 is connected with the storage bin 6, that is, the outlet of the second vibrating screen 4 and the storage bin 6 are connected through the first conveyor line 7, so that the lithium iron phosphate powder screened by the second vibrating screen 4 can be transported to the storage bin 6 for storage through the first conveyor line 7, realizing the automatic transportation and automatic storage of the lithium iron phosphate powder, which is easy to use and improves work efficiency.

[0232] In a specific implementation, the lithium iron phosphate powder screened by the second vibrating screen 4 is discharged from the outlet of the second vibrating screen 4 and then enters the first conveyor line 7. Then, under the conveyance of the first conveyor line 7, it enters the storage bin 6, realizing the automatic recovery and storage of the lithium iron phosphate powder, improving the automation level of lithium iron phosphate powder recovery, making recovery more convenient and facilitating subsequent use.

[0233] In some embodiments, reference Figure 3 and Figure 5 As shown, at least one fool-proof structure 5 is provided on the first conveyor line 7, and the fool-proof structure 5 is electrically connected to the first conveyor line 7. The fool-proof structure 5 is used to detect the lithium iron phosphate powder. The first conveyor line 7 is used to stop when the fool-proof structure 5 detects metal foreign matter in the lithium iron phosphate powder.

[0234] By arranging an anti-foolproof structure 5 on the first conveyor line 7, the lithium iron phosphate powder is detected by the anti-foolproof structure 5, and the first conveyor line 7 can stop conveying the lithium iron phosphate powder into the storage bin 6 when the anti-foolproof structure 5 detects metal foreign matter in the lithium iron phosphate powder. The degree of automation is high, the use is convenient, and the recovery efficiency of the lithium iron phosphate powder is guaranteed to a certain extent.

[0235] In some implementations, a plurality of fool-proof structures 5 are provided on the first conveyor line 7, and the plurality of fool-proof structures 5 are spaced apart along the length direction of the first conveyor line 7. With such a configuration, the detection effect of metal foreign matter in the lithium iron phosphate powder is better, and the recovery purity of the lithium iron phosphate powder is further improved.

[0236] For example, refer to Figure 2 As shown, three fool-proof structures 5 are arranged at intervals along the length direction of the first conveyor line 7.

[0237] In specific implementation, the fool-proof structure 5 can be, for example, a cleanliness analyzer.

[0238] The cleanliness analyzer can, for example, analyze the cleanliness of the lithium iron phosphate powder by irradiating the lithium iron phosphate powder on the first conveyor line 7 with a light source and measuring whether the lithium iron phosphate powder reflects light.

[0239] In specific implementation, the cleanliness analyzer performs detection by irradiating the lithium iron phosphate powder on the first conveyor line 7 with a light source.

[0240] If there is no metal foreign matter in the lithium iron phosphate powder, the cleanliness analyzer will not collect reflected light when the lithium iron phosphate powder passes through the cleanliness analyzer, and it is considered that there is no metal foreign matter in the lithium iron phosphate powder passing through the cleanliness analyzer.

[0241] If the lithium iron phosphate powder is mixed with metal foreign matter, the cleanliness analyzer can collect reflected light when the lithium iron phosphate powder passes through the cleanliness analyzer, and it is considered that the lithium iron phosphate powder passing through the cleanliness analyzer is mixed with metal foreign matter. At the same time, the first conveyor line 7 stops working, so as to ensure that the lithium iron phosphate powder mixed with metal foreign matter will not enter the storage bin 6, thereby improving the recovery quality of the lithium iron phosphate powder.

[0242] In some embodiments, reference Figure 4 and Figure 5 As shown, the lithium iron phosphate recovery device further includes a second conveyor line 8 , one end of the second conveyor line 8 is connected to the outlet of the second vibrating screen 4 , and the other end of the second conveyor line 8 is connected to the feed port of the grinding equipment 3 .

[0243] The outlet of the second vibrating screen 4 and the feed port of the grinding equipment 3 are connected by the second conveyor line 8, so that the lithium iron phosphate powder screened by the second vibrating screen 4 can be returned to the grinding equipment 3 through the second conveyor line 8 for further grinding. In other words, the setting of the second conveyor line 8 realizes the re-grinding of the lithium iron phosphate powder, further improves the separation efficiency of the lithium iron phosphate and the metal, and thus further improves the recovery purity of the lithium iron phosphate powder.

[0244] In some implementations, reference Figure 4 As shown, the second conveying line 8 and the outlet of the second vibrating screen 4 can be directly connected, for example.

[0245] In other implementations, reference Figure 5 As shown, one end of the second conveyor line 8 is connected to the outlet of the second vibrating screen 4 through the first conveyor line 7, that is, the second conveyor line 8 is connected to the outlet of the second vibrating screen 4 through the inlet side of the first conveyor line 7, so that when the anti-foolproof structure 5 detects that there are metal foreign matter in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line 7 can be returned to the grinding equipment 3 through the second conveyor line 8 to be ground again.

[0246] In specific implementation, when the fool-proof structure 5 detects that there are metal foreign objects in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line 7 can be returned to the grinding equipment 3 through the second conveyor line 8, so that the grinding equipment 3 can continue to grind the returned lithium iron phosphate powder, further improving the degree of automation of lithium iron phosphate powder recovery and the recovery efficiency of lithium iron phosphate powder, and ensuring the recovery quality of lithium iron phosphate powder.

[0247] In summary, when the lithium iron phosphate recovery device provided in this embodiment is used to recover the lithium iron phosphate on the lithium iron phosphate pole piece in the waste lithium iron phosphate battery, the specific operations are as follows:

[0248] The waste lithium iron phosphate electrode is fed into the crushing structure 1 for crushing to obtain crushed material. The crushed material is screened through the first vibrating screen 2 to obtain the primary screened material. The primary screened material is then fed into the grinding equipment 3 for grinding to obtain the grinding material, wherein the grinding material includes metal foil and lithium iron phosphate powder. The grinding material is then screened through the second vibrating screen 4 to obtain the lithium iron phosphate powder to be recycled. Compared with the solution of using chemical reagent leaching process in the related art, there is no need to use chemical reagents, and the physical recovery of lithium iron phosphate is achieved, thereby avoiding the environmental pollution caused by the use of chemical reagents, and will not cause secondary pollution, reducing the subsequent processing costs, and thus reducing the recovery cost of lithium iron phosphate to a certain extent. At the same time, it also avoids the phenomenon of metal foil corrosion caused by the use of chemical reagents, thereby improving the recovery quality of metals.

[0249] In addition, compared with the solution of mechanically stripping lithium iron phosphate from the electrode in the prior art, this method avoids the occurrence of lithium iron phosphate residue on the electrode to a certain extent, realizes the effective recovery of lithium iron phosphate materials, and improves the recovery efficiency and purity of lithium iron phosphate.

[0250] Furthermore, the outlet of the second vibrating screen 4 is connected to the storage bin 6 via a first conveyor line 7, and a fool-proof structure 5 is provided on the first conveyor line 7 to detect the lithium iron phosphate powder on the first conveyor line 7. When the fool-proof structure 5 does not sound an alarm, the lithium iron phosphate powder on the first conveyor line 7 is conveyed to the storage bin 6. When the fool-proof structure 5 sounds an alarm, the lithium iron phosphate powder on the first conveyor line 7 is conveyed to the storage bin 6 via a second conveyor line 8 for further grinding. In other words, the lithium iron phosphate powder can only enter the storage bin 6 for storage via the first conveyor line 7 when the fool-proof structure 5 does not sound an alarm, thereby ensuring the recovery efficiency and quality of the lithium iron phosphate powder.

[0251] In other words, through the crushing, grinding, and screening processes, lithium iron phosphate can be effectively separated from the waste lithium iron phosphate electrode sheets, improving recycling efficiency. At the same time, the foolproof structure 5 on the first conveyor line 7 prevents metallic foreign matter from entering the storage bin 6, ensuring the recovery quality of the lithium iron phosphate powder. Furthermore, combined with ICP testing of the lithium iron phosphate powder in the storage bin 6, the operating parameters of the roller press can be adjusted, further ensuring the recovery efficiency and quality of the lithium iron phosphate powder.

[0252] At the same time, compared with the solution of using a large amount of chemical reagents to recover lithium iron phosphate, the recovery cost is reduced and the environmental pollution caused by chemical reagents is avoided.

[0253] The following four embodiments and three comparative examples more intuitively demonstrate the various performance conditions of lithium iron phosphate recovered by the method for recovering lithium iron phosphate of battery pole pieces provided by this embodiment using a lithium iron phosphate recovery device.

[0254] Example 1:

[0255] 50kg of waste lithium iron phosphate electrodes are fed into the pulverization structure 1 for pulverization to obtain pulverized material. The pulverized material is screened through a first vibrating screen 2 with a mesh size of 80 to obtain pre-screened material. The pre-screened material is then fed into the grinding equipment 3 for grinding. The grinding equipment 3 includes an upper and lower roller structure 9. Each roller structure 9 has four rotating rollers 92 and three fixed rollers 91. From a horizontal perspective, the two outermost rotating rollers 92 of each roller structure 9 rotate inward, the pressure of the rotating rollers 92 is 100T, the roller gap is 100μm, and the rotation speed of the rotating rollers 92 is 2m / s. After three grinding processes, the ground material is screened through a second vibrating screen 4 with a mesh size of 150 to obtain lithium iron phosphate powder.

[0256] Three fool-proof structures 5 are set on the first conveyor line 7 to detect the lithium iron phosphate powder. Only when the three fool-proof structures 5 do not sound an alarm can the lithium iron phosphate powder enter the storage bin and obtain qualified lithium iron phosphate powder. 5g of lithium iron phosphate powder is extracted from the storage bin 6 for IPC test, processing performance test and electrical performance test. The test results are referenced. Figure 5 and Figure 6 .

[0257] Example 2:

[0258] 50 kg of waste lithium iron phosphate electrodes were fed into a pulverizing structure 1 for pulverization, yielding a pulverized material. The pulverized material was then screened through a first vibrating screen 2 with an 80-mesh screen to yield a pre-screened material. The pre-screened material was then fed into a grinding device 3 for grinding. The grinding device 3 comprises a three-stage roller structure 9: the top roller structure 9 comprises six rotating rollers 92 and three fixed rollers 91; the middle roller structure 9 comprises four rotating rollers 92 and two fixed rollers 91; and the bottom roller structure 9 comprises two rotating rollers 92 and one fixed roller 91. Horizontally, the two outermost rotating rollers 92 of each roller structure 9 rotate inward, with a pressure of 100 T, a roller gap of 100 μm, and a rotational speed of 2 m / s. After three grinding steps, the ground material was screened through a second vibrating screen 4 with a 150-mesh screen to yield lithium iron phosphate powder.

[0259] Three fool-proof structures 5 are set on the first conveyor line 7 to detect the lithium iron phosphate powder. Only when the three fool-proof structures 5 do not sound an alarm can the lithium iron phosphate powder enter the storage bin and obtain qualified lithium iron phosphate powder. 5g of lithium iron phosphate powder is extracted from the storage bin 6 for ICP test, processing performance test and electrical performance test. The test results are referenced. Figure 5 and Figure 6 .

[0260] Example 3:

[0261] 50kg of waste lithium iron phosphate electrodes are fed into a pulverizing structure 1 for pulverization to obtain pulverized material. The pulverized material is screened through a first vibrating screen 2 with a mesh size of 80 to obtain a pre-screened material. The pre-screened material is then fed into a grinding device 3 for grinding. The grinding device 3 comprises an upper and lower roller structure 9. Each roller structure 9 has four rotating rollers 92 and three fixed rollers 91. Horizontally, the two outermost rotating rollers 92 of each roller structure 9 rotate inward, with a pressure of 100T, a roller gap of 100μm, and a rotation speed of 2m / s. After one grinding process, the ground material is screened through a second vibrating screen 4 with a mesh size of 150 to obtain lithium iron phosphate powder.

[0262] Three fool-proof structures 5 are set on the first conveyor line 7 to detect the lithium iron phosphate powder. Only when the three fool-proof structures 5 do not sound an alarm can the lithium iron phosphate powder enter the storage bin and obtain qualified lithium iron phosphate powder. 5g of lithium iron phosphate powder is extracted from the storage bin 6 for ICP test, processing performance test and electrical performance test. The test results are referenced. Figure 5 and Figure 6 .

[0263] Example 4:

[0264] 50kg of waste lithium iron phosphate electrodes are fed into the pulverizing structure 1 for pulverization to obtain pulverized material. The pulverized material is screened through a first vibrating screen 2 with a mesh size of 80 to obtain pre-screened material. The pre-screened material is then fed into the grinding equipment 3 for grinding. The grinding equipment 3 includes an upper and lower roller structure 9. Each roller structure 9 has four rotating rollers 92 and three fixed rollers 91. From a horizontal perspective, the two outermost rotating rollers 92 of each roller structure 9 rotate inward, the pressure of the rotating rollers 92 is 50T, the roller gap is 200μm, and the rotation speed of the rotating rollers 92 is 3m / s. After the first grinding process, the ground material is screened through a second vibrating screen 4 with a mesh size of 150 to obtain lithium iron phosphate powder.

[0265] Three fool-proof structures 5 are set on the first conveyor line 7 to detect the lithium iron phosphate powder. Only when the three fool-proof structures 5 do not sound an alarm can the lithium iron phosphate powder enter the storage bin and obtain qualified lithium iron phosphate powder. 5g of lithium iron phosphate powder is extracted from the storage bin 6 for ICP test, processing performance test and electrical performance test. The test results are referenced. Figure 5 and Figure 6 .

[0266] It can be seen from Example 1 and Example 2 that, when the mesh number of the first vibrating screen 2 is the same, the mesh number of the second vibrating screen 4 is the same, the number of rolling times is the same, and the working parameters of the grinding equipment 3 are the same, the processing performance and electrical properties of the lithium iron phosphate powder obtained by the three-stage roller structure treatment in Example 2 are better than the processing performance and electrical properties of the lithium iron phosphate powder obtained by the two-stage roller structure treatment in Example 1. In other words, when the mesh number of the first vibrating screen 2 is the same, the mesh number of the second vibrating screen 4 is the same, the number of rolling times is the same, and the working parameters of the grinding equipment 3 are the same, the more levels of the roller structure, the better the processing performance and electrical properties of the lithium iron phosphate powder. The test results refer to Figure 6 shown.

[0267] And, reference Figure 5 and Figure 6 As shown, the copper content and aluminum content of the lithium iron phosphate powder obtained in Example 2 are respectively smaller than the copper content and aluminum content of the lithium iron phosphate powder obtained in Example 1. It can be seen that when the mesh size of the first vibrating screen is the same, the mesh size of the second vibrating screen is the same, the number of rolling times is the same, and the working parameters of the grinding equipment 3 are the same, the more levels of the roller structure, the lower the copper content and aluminum content in the lithium iron phosphate powder, and the higher the recovery purity.

[0268] It can be seen from Examples 1 and 3 that, when the mesh number of the first vibrating screen 2 is the same, the mesh number of the second vibrating screen 4 is the same, the level of the roller structure 9 in the grinding equipment 3 is the same, the structure is the same, and the working parameters are the same, the processing performance and electrical properties of the lithium iron phosphate powder obtained after three rolling treatments in Example 1 are better than the processing performance and electrical properties of the lithium iron phosphate powder obtained after one rolling treatment in Example 3. In other words, when the mesh number of the first vibrating screen 2 is the same, the mesh number of the second vibrating screen 4 is the same, the level of the roller structure 9 in the grinding equipment 3 is the same, the structure is the same, and the working parameters are the same, the more times the rolling treatment is performed, the better the processing performance and electrical properties of the lithium iron phosphate powder. The test results refer to Figure 6 shown.

[0269] It can be seen from Examples 3 and 4 that, when the mesh number of the first vibrating screen 2 is the same, the mesh number of the second vibrating screen 4 is the same, the level of the roller structure 9 in the grinding equipment 3 is the same, the structure is the same, and the number of rolling times is the same, although the grinding pressure, roller gap, and rotating roller speed of the grinding equipment 3 in Example 3 are respectively greater than the grinding pressure, roller gap, and rotating roller speed of the grinding equipment 3 in Example 4, the processing performance of the lithium iron phosphate powder obtained in Example 3 is the same as the processing performance of the lithium iron phosphate powder obtained in Example 4, and the electrical properties of the lithium iron phosphate powder obtained in Example 3 are roughly equal to the electrical properties of the lithium iron phosphate powder obtained in Example 4. That is to say, when the mesh number of the first vibrating screen 2 is the same, the mesh number of the second vibrating screen 4 is the same, the level of the roller structure 9 in the grinding equipment 3 is the same, the structure is the same, and the number of rolling times is the same, the processing performance and electrical properties of the lithium iron phosphate powder are roughly equal. Figure 6 shown.

[0270] And, reference Figure 5 and Figure 6 As shown, the copper content and aluminum content of the lithium iron phosphate powder obtained in Example 3 are respectively greater than the copper content and aluminum content of the lithium iron phosphate powder obtained in Example 4. It can be seen that when the mesh size of the first vibrating screen 2 is the same, the mesh size of the second vibrating screen 4 is the same, the level and structure of the roller structure 9 in the grinding equipment 3 are the same, and the number of rolling times is the same, the greater the grinding pressure of the grinding equipment 3 and / or the smaller the roller gap and / or the faster the rotation speed of the rotating roller, the lower the copper and aluminum contents in the recovered lithium iron phosphate powder, and the higher the purity of the recovered lithium iron phosphate powder.

[0271] Comparative Example 1

[0272] The lithium iron phosphate material recovered by pyrolysis was used for ICP test, processing performance test and electrical performance test. The test results are referenced Figure 5 and Figure 6 shown.

[0273] Comparative Example 2

[0274] The lithium iron phosphate powder recovered by mechanical stripping is subjected to ICP test, processing performance test and electrical performance test. The test results are referenced Figure 5 and Figure 6 shown.

[0275] Comparative Example 3

[0276] The unprocessed lithium iron phosphate powder (raw material for making lithium iron phosphate pole pieces) is tested for ICP, processing performance and electrical performance. The test results are referenced to Figure 5 and Figure 6 shown.

[0277] From this we can see that the reference Figure 5 and Figure 6 As shown, the copper content and aluminum content of the lithium iron phosphate powder recovered in Comparative Example 1 ranked second, which were much larger than the copper content and aluminum content in Comparative Example 3, respectively. In addition, the processing performance and electrical properties of the lithium iron phosphate powder recovered in Comparative Example 1 were much lower than those in Comparative Example 3.

[0278] The lithium iron phosphate powder recovered in Comparative Example 2 has the highest copper content, the highest aluminum content, the worst processing performance, and the lowest electrical properties. That is to say, the copper content and aluminum content of the lithium iron phosphate powder recovered in Comparative Example 2 are much greater than the copper content and aluminum content in Comparative Example 3, respectively, and the processing performance and electrical properties of the lithium iron phosphate powder recovered in Comparative Example 2 are much lower than those in Comparative Example 3.

[0279] The lithium iron phosphate material of waste lithium iron phosphate pole pieces was recovered by adopting the method for recycling lithium iron phosphate of battery pole pieces provided in this embodiment. The copper content, aluminum content, processing performance, and electrical properties of the lithium iron phosphate powder obtained in Example 1, Example 2, Example 3, and Example 4 were similar to those in Comparative Example 3. After optimizing the parameters of the grinding equipment 3, it can be seen that the copper content, aluminum content, processing performance, and electrical properties of the lithium iron phosphate powder recovered in Example 2 are closest to those in Comparative Example 3, respectively.

[0280] That is to say, by comparing Example 2 with Comparative Example 3, it can be seen that the copper content, aluminum content, processing performance, and electrical properties of the two are relatively similar. That is, the lithium iron phosphate material is recycled by the lithium iron phosphate recycling method of the battery pole piece provided by this embodiment. The recycled lithium iron phosphate material on the waste lithium iron phosphate pole piece can reach the level of the unprocessed lithium iron phosphate powder in Comparative Example 3 and can be used for subsequent production.

[0281] It can be seen that the lithium iron phosphate material recovered by the lithium iron phosphate recovery method of the battery electrode provided in this embodiment is far superior to the lithium iron phosphate material recovered by the fire method and mechanical stripping of the related technology, thereby realizing the efficient recovery of lithium iron phosphate, and does not affect the subsequent processing performance and electrical properties of the lithium iron phosphate. At the same time, it effectively prevents metal substances such as aluminum and copper from entering the storage bin, thereby improving the recovery purity. Moreover, there is no need to use chemical reagents, and the physical recovery of lithium iron phosphate is realized, avoiding the environmental pollution caused by the use of chemical reagents, and will not cause secondary pollution, thereby reducing the subsequent processing costs, and thus reducing the recovery cost of lithium iron phosphate to a certain extent.

Claims

1. A method for recovering lithium iron phosphate from battery pole pieces, characterized in that: include: Crushing the pole pieces to obtain crushed materials; sieving the crushed material to obtain a primary screened material; Grinding the pre-screened material with a grinding device to obtain a ground material, wherein the ground material includes metal foil and lithium iron phosphate powder; The ground material is sieved to separate the metal foil and the lithium iron phosphate powder to obtain the lithium iron phosphate powder.

2. The method for recycling lithium iron phosphate of battery pole pieces according to claim 1, characterized in that: The grinding equipment has a roller structure therein, and the roller structure is used to grind the pre-screened material to obtain the metal foil and lithium iron phosphate powder.

3. The method for recycling lithium iron phosphate of battery pole pieces according to claim 2, characterized in that: The roller structure includes at least one fixed roller and at least two rotating rollers, the fixed roller and the rotating rollers are arranged in the horizontal direction, and a fixed roller is arranged between at least two adjacent rotating rollers, and the roller gap between adjacent fixed rollers and rotating rollers is 10μm-200μm, and the roller gap between two adjacent rotating rollers is 10μm-200μm.

4. The method for recycling lithium iron phosphate of battery pole pieces according to claim 3, characterized in that: The two rollers of the roller structure located on the outermost sides in the horizontal direction are both rotating rollers, and when viewed from above in the horizontal direction, the rotation direction of the two rotating rollers located on the outermost sides is inward; And / or, the grinding pressure of the rotating roller is 50T-200T; And / or, the rotation speed of the rotating roller is 1 m / s-5 m / s.

5. The method for recycling lithium iron phosphate of battery pole pieces according to claim 2, characterized in that: The roller structure has at least two levels, and the at least two levels of roller structures are arranged in sequence along the vertical direction, and the roller gaps of the two adjacent levels of roller structures are staggered in the vertical direction; And / or, the grinding pressure of the grinding equipment is 50T-200T; And / or, the grinding equipment includes a roller press.

6. The method for recycling lithium iron phosphate of battery pole pieces according to claim 1, characterized in that: The grinding equipment performs at least two-stage grinding treatment on the pre-screened material.

7. The method for recycling lithium iron phosphate from battery pole pieces according to any one of claims 1 to 6, characterized in that: crushing the pole piece by a crushing structure; and / or, screening the pulverized material through a first vibrating screen; The mesh number of the first vibrating screen is not greater than 80 mesh; and / or, screening the ground material through a second vibrating screen; The mesh number of the second vibrating screen is 100-120 mesh.

8. The method for recycling lithium iron phosphate of battery pole pieces according to any one of claims 1 to 6, characterized in that: The method for recovering lithium iron phosphate from the battery pole piece further comprises: The lithium iron phosphate powder is transported to a storage bin through a first conveying line.

9. The method for recycling lithium iron phosphate of battery pole pieces according to claim 8, characterized in that: At least one fool-proof structure is provided on the first conveyor line, the fool-proof structure is electrically connected to the first conveyor line, the fool-proof structure is used to detect the lithium iron phosphate powder, and the first conveyor line is used to stop when the fool-proof structure detects metal foreign matter in the lithium iron phosphate powder; The foolproof structure includes a cleanliness analyzer.

10. The method for recycling lithium iron phosphate of battery pole pieces according to claim 9, characterized in that: The method for recovering lithium iron phosphate from the battery pole piece further comprises: When the fool-proof structure detects that there are metallic foreign objects in the lithium iron phosphate powder, the lithium iron phosphate powder on the first conveyor line is returned to the grinding equipment through the second conveyor line to be ground again.

11. The method for recycling lithium iron phosphate of battery pole pieces according to claim 8, characterized in that: The method for recovering lithium iron phosphate from the battery pole piece further comprises: Element detection is performed on the lithium iron phosphate powder in the storage bin, and when the aluminum content is greater than a first preset threshold and / or the copper content is greater than a second preset threshold, the working parameters of the grinding equipment are adjusted.

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