A device for recycling battery-grade lithium carbonate from solid waste and a recycling process thereof

Abstract

The application provides a device for recycling battery-grade lithium carbonate from solid waste and a recycling process thereof, and relates to the technical fields of resource recycling and battery material preparation. The device comprises a bearing frame, a production tank and an injection mechanism. The production tank is located at the inner middle position of the bearing frame. A top cover is fixedly installed on the top of the production tank. A top plate is fixedly arranged on the upper surface of the top cover. An installation frame is fixedly installed on the upper surface of the top plate. A leaching motor is installed on the top of the installation frame. A key rod is connected to the output shaft key groove of the leaching motor. A mixing frame is fixedly installed at the bottom end of the key rod and in the production tank. The three groups of spray pipes are vertically arranged in layers, which can cover all the reaction areas in the production tank in all directions without dead angles. The spraying coverage area of the deionized water is greatly widened. During the water injection process, the water flow is uniformly dispersed in the form of a fan shape and falls down, which can layer by layer infiltrate and disperse the lithium iron phosphate positive electrode powder in the tank, and can avoid the problems of positive electrode powder accumulation, agglomeration and caking.

Description

Technical Field

[0001] This invention relates to the field of resource recycling and battery material preparation, and in particular to a device and recycling process for recycling battery-grade lithium carbonate from solid waste. Background Technology

[0002] Lithium iron phosphate batteries have been widely used in electric vehicles and energy storage due to their advantages such as high safety, long cycle life, and low cost. As early installed batteries gradually enter their retirement period, the recycling and disposal of waste lithium iron phosphate batteries has become a resource and environmental problem to be solved. Waste lithium iron phosphate batteries lose their energy storage value after use and pose multiple ecological and health hazards. They are classified as general industrial solid waste and must be recycled and disposed of in accordance with solid waste management standards.

[0003] However, used lithium iron phosphate batteries contain useful lithium carbonate, so they need to be recycled. Battery-grade lithium carbonate is the core raw material for producing ternary lithium battery cathode materials. With the continuous development of lithium-ion batteries and energy storage batteries, and the increasing demand for clean, environmentally friendly, and healthy performance in downstream applications, the application scope of lithium will be further expanded.

[0004] In existing technologies, there are many dead zones in the production tank, which prevents deionized water from quickly and completely merging with lithium iron phosphate cathode powder. This easily leads to the cathode powder accumulating and clumping locally at the bottom and walls of the tank, causing some lithium iron phosphate particles to not react completely, significantly reducing the lithium leaching rate, and increasing raw material loss.

[0005] Therefore, it is necessary to provide a device and recycling process for recovering battery-grade lithium carbonate from solid waste to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a device and process for recycling battery-grade lithium carbonate from solid waste, which solves the problem in related technologies where there are many fluid dead zones in the production tank, and deionized water and lithium iron phosphate cathode powder cannot be quickly and completely integrated.

[0007] To solve the above-mentioned technical problems, the present invention provides a device for recycling battery-grade lithium carbonate from solid waste, comprising a support frame, a production tank and an injection mechanism;

[0008] The production tank is located in the middle of the inside of the support frame. A top cover is fixedly installed on the top of the production tank. A top plate is fixedly installed on the upper surface of the top cover. An installation frame is fixedly installed on the upper surface of the top plate. An leaching motor is installed on the top of the installation frame. A key rod is connected to the output shaft of the leaching motor via a keyway. A mixing frame is fixedly installed at the bottom of the key rod inside the production tank.

[0009] The injection mechanism includes a positioning frame mounted on the upper surface of the top cover and located on one side of the mounting bracket. An injection motor is mounted on the top of the positioning frame. The output shaft of the injection motor is connected to a first pulley via a keyway. A double-groove pulley and a second pulley are rotatably mounted inside the top cover and on one side of the first pulley. A synchronous belt is sleeved on the outer wall of the first pulley, the double-groove pulley, and the second pulley.

[0010] The first pulley, the double-groove pulley, and the second pulley are respectively keyway connected to the first drive wheel, the second drive wheel, and the third drive wheel at their shaft centers and below the top cover;

[0011] The injection mechanism also includes two driven wheels, with nozzles installed at the shaft centers of the two driven wheels and the shaft center of the second drive wheel, and a transmission ring rotatably connected at the center of the top cover.

[0012] Preferably, the first drive wheel, the second drive wheel, and the third drive wheel are in close contact with the outer walls of the two driven wheels and the inner wall of the transmission ring.

[0013] Preferably, the first drive wheel, the second drive wheel, and the third drive wheel are equidistantly distributed in a ring with the two driven wheels about the axis of the transmission ring.

[0014] Preferably, it also includes a material distribution mechanism;

[0015] The material distribution mechanism includes a positioning plate fixed to the inner wall of the transmission ring, and a reciprocating rotating material distribution plate is integrally provided on the outer wall of the positioning plate.

[0016] Preferably, the material distribution plate is directly opposite the outlet of the discharge pipe, and the material distribution plate is eccentrically positioned about the axis of the transmission ring.

[0017] Preferably, it also includes auxiliary mechanisms;

[0018] A sliding sleeve is slidably installed on the outer wall of the key rod, and a lifting plate is fixedly installed at the top of the sliding sleeve. The auxiliary mechanism includes a sleeve fixed inside the mounting frame, a piston slidably installed inside the sleeve, a through hole opened inside the piston, an inlet pipe and an outlet pipe installed through both sides of the sleeve, a spring rod fixedly installed at the bottom end of the piston, and a guide wheel installed at the bottom end of the spring rod.

[0019] Preferably, the spring rod slides about the sleeve in the vertical direction, the outer wall of the guide wheel and the upper surface of the lifting plate are in contact with each other, and the outlet end of the discharge pipe is located on the upper surface of the distribution plate.

[0020] The process for recovering battery-grade lithium carbonate from solid waste includes the following steps:

[0021] S1: Preprocessing;

[0022] Waste lithium iron phosphate batteries are discharged and disassembled to obtain positive electrode sheets. The positive electrode sheets are then heat-treated in an inert atmosphere to remove the binder and peeled off to obtain lithium iron phosphate positive electrode powder.

[0023] S2: Preparation of iron single-atom catalyst;

[0024] Iron salts and nitrogen-containing organic matter were dissolved in deionized water, carbon support was added, the mixture was ultrasonically dispersed and dried, and the dried product was pyrolyzed under an inert atmosphere to obtain an iron single-atom catalyst.

[0025] S3: Advanced oxidative leaching;

[0026] The lithium iron phosphate cathode powder obtained in S1 was dispersed in deionized water, and the iron single-atom catalyst prepared in S2 was added.

[0027] Adjust the pH of the solution and add hydrogen peroxide solution dropwise under stirring to fully leach out the solution;

[0028] Leaching must be performed in equipment that utilizes solid waste to recycle battery-grade lithium carbonate.

[0029] S4: Lithium carbonate precipitate;

[0030] The lithium-containing leachate obtained from S3 was concentrated, and a saturated sodium carbonate solution was slowly added under stirring. After standing and aging, the crude lithium carbonate was obtained by filtration.

[0031] S5: Washing and purification;

[0032] The crude lithium carbonate obtained from S4 was washed with hot water and dried to obtain battery-grade lithium carbonate product.

[0033] Compared with related technologies, the device and recycling process for recycling battery-grade lithium carbonate from solid waste provided by this invention have the following advantages:

[0034] The three sets of nozzles adopt a vertical layered layout, combined with the fan-shaped spray coverage formed by synchronous rotation, which can cover all reaction areas inside the production tank in an all-round and dead-angle manner, greatly expanding the spray coverage area of ​​deionized water. During the water injection process, the water flow falls evenly in a fan-shaped diffused manner, which can wet and disperse the lithium iron phosphate cathode powder in the tank layer by layer, thereby avoiding the problems of cathode powder accumulation, agglomeration and clumping from the root. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0036] Figure 1 The optimal structural schematic diagram provided for this invention;

[0037] Figure 2 for Figure 1 The diagram shows a top view of the structure.

[0038] Figure 3 for Figure 1 The diagram shows a cross-sectional view of the production tank.

[0039] Figure 4 for Figure 3 The diagram shows the overall top-view structure.

[0040] Figure 5 The present invention provides a schematic diagram of the working principle of the injection mechanism, wherein (a) is a schematic diagram of the initial working state of the three nozzles, and (b) is a schematic diagram of the working state in which the transmission ring is driven to rotate and synchronously drives the three nozzles to form a fan-shaped spray range.

[0041] Figure 6 This is a cross-sectional structural diagram of the auxiliary mechanism provided by the present invention;

[0042] Figure 7 The diagram shows the working principle of the material distribution mechanism provided by the present invention, wherein (c) is a schematic diagram of the initial working state of the material distribution plate located at the bottom of the discharge pipe, and (d) is a schematic diagram of the working state of the material distribution plate being rotated synchronously during the rotation of the transmission ring.

[0043] Explanation of icon numbers:

[0044] 1. Support frame; 2. Production tank; 3. Top cover;

[0045] 4. Mounting bracket; 5. Immersion motor; 6. Top plate;

[0046] 7. Injection mechanism; 71. Positioning frame; 72. Injection motor; 73. First pulley; 74. Double groove pulley; 75. Second pulley; 76. Synchronous belt; 77. Nozzle; 78. First drive wheel; 79. Second drive wheel; 710. Third drive wheel; 711. Driven wheel; 712. Transmission ring.

[0047] 8. Material distribution mechanism; 81. Positioning plate; 82. Material distribution plate;

[0048] 9. Auxiliary mechanism; 91. Sleeve; 92. Inlet pipe; 93. Discharge pipe; 94. Piston; 95. Through hole; 96. Spring rod; 97. Guide wheel;

[0049] 10. Key lever; 11. Sliding sleeve;

[0050] 12. Lifting plate; 13. Mixing rack. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] This invention provides a device and recycling process for recovering battery-grade lithium carbonate from solid waste.

[0053] First embodiment:

[0054] Please see Figures 1 to 5 A device for recycling battery-grade lithium carbonate from solid waste includes a support frame 1, a production tank 2, and an injection mechanism 7.

[0055] The production tank 2 is located in the middle of the inside of the support frame 1. A top cover 3 is fixedly installed on the top of the production tank 2. A top plate 6 is fixedly installed on the upper surface of the top cover 3. A mounting frame 4 is fixedly installed on the upper surface of the top plate 6. An leaching motor 5 is installed on the top of the mounting frame 4. A key rod 10 is connected to the key shaft of the leaching motor 5. A mixing frame 13 is fixedly installed at the bottom of the key rod 10 and inside the production tank 2.

[0056] The injection mechanism 7 includes a positioning frame 71 mounted on the upper surface of the top cover 3 and located on one side of the mounting frame 4. An injection motor 72 is mounted on the top of the positioning frame 71. The output shaft of the injection motor 72 is keyway connected to a first pulley 73. A double-groove pulley 74 and a second pulley 75 are rotatably mounted inside the top cover 3 and on one side of the first pulley 73. A synchronous belt 76 is sleeved on the outer wall of the first pulley 73, the double-groove pulley 74 and the second pulley 75.

[0057] The first pulley 73, the double-groove pulley 74, and the second pulley 75 are respectively keyway connected to the first drive wheel 78, the second drive wheel 79, and the third drive wheel 710 at the shaft center and below the top cover 3;

[0058] The injection mechanism 7 also includes two driven wheels 711, and a nozzle 77 is installed at the axis of the two driven wheels 711 and the axis of the second drive wheel 79. A transmission ring 712 is rotatably connected at the center of the top cover 3.

[0059] The first drive wheel 78, the second drive wheel 79 and the third drive wheel 710 are in close contact with the outer walls of the two driven wheels 711 and the inner wall of the transmission ring 712.

[0060] The first drive wheel 78, the second drive wheel 79, and the third drive wheel 710 are equidistantly distributed in a ring with the two driven wheels 711 about the axis of the transmission ring 712.

[0061] Please see Figures 1 to 3 During leaching, the leaching motor 5 is activated to control the rotation of the control lever 10.

[0062] Please see Figures 1 to 3 The key rod 10 can control the mixing frame 13 to rotate inside the production tank 2, thereby fully mixing and leaching the waste lithium iron phosphate cathode powder and deionized water inside the production tank 2.

[0063] Please see Figure 4 During leaching, the user starts the injection motor 72 to drive the first pulley 73 to rotate. When the first pulley 73 rotates, the transmission timing belt 76 controls the double groove pulley 74 and the second pulley 75 to rotate synchronously in the same direction.

[0064] The first pulley 73, the double-groove pulley 74, and the second pulley 75 extend axially downward to the inner side of the top cover 3, and are rigidly connected to the first drive wheel 78, the second drive wheel 79, and the third drive wheel 710 made of rubber, respectively, forming a complete set of active friction transmission units.

[0065] The first drive wheel 78, the second drive wheel 79, and the third drive wheel 710 are rubber friction wheels. The outer circular surface of the wheel is tightly attached to the inner ring wall of the annular transmission ring 712, and the two form an annular friction pair.

[0066] Torque is transmitted by static friction between the rubber and the metal transmission ring 712. When the first drive wheel 78, the second drive wheel 79 and the third drive wheel 710 rotate on their own, circumferential friction is generated at the contact point between the wheel body and the inner wall of the transmission ring 712. The friction drives the hollow transmission ring 712 to make an overall circular rotation around its own central axis.

[0067] The three-point synchronous friction drive design can distribute the contact pressure, avoid single-point slippage, ensure that the transmission ring 712 rotates smoothly and without deviation, and can realize forward and reverse reciprocating rotation.

[0068] Please see Figure 3 and Figure 4 The first pulley 73, the double-groove pulley 74, and the second pulley 75 drive the corresponding first drive wheel 78, second drive wheel 79, and third drive wheel 710 to rotate in the transmission ring 712. During the rotation of the transmission ring 712, the two driven wheels 711 rotate synchronously.

[0069] Please see Figure 5 In (a): In the initial state, all three nozzles 77 are oriented outwards.

[0070] Please see Figure 5(b) In this case, since the second drive wheel 79 and the two driven wheels 711 rotate synchronously in the same direction, the spray range of the three outward-facing nozzles 77 is controlled to rotate from the initial outer side to the inner side to spray deionized water, thereby achieving a fan-shaped trajectory spray. At the same time, the reverse rotation can control the three nozzles 77 to reset. Therefore, during the injection of deionized water, the transmission ring 712 needs to reciprocate to control the reciprocating rotation of the three nozzles 77.

[0071] Understandable: The top water inlet of the three nozzles 77 can be externally mounted with a rotary joint and an externally mounted deionized water supply tank.

[0072] In one application scenario, the equipment for recycling battery-grade lithium carbonate from solid waste can be used to extract lithium from lithium-containing iron-phosphate solid slag precipitated from waste residue and waste mother liquor produced from iron phosphate precursor production.

[0073] When extracting lithium from lithium-containing iron-phosphorus solid slag precipitated from waste residue and waste mother liquor of iron phosphate precursor production, the lithium-containing iron-phosphorus solid slag precipitated from waste residue and waste mother liquor of iron phosphate precursor production is placed in production tank 2 to participate in water leaching lithium extraction. The specific lithium extraction process is as described above.

[0074] In another application, the equipment for recycling battery-grade lithium carbonate from solid waste can also be used to extract lithium from mixed powder solid wastewater during the entire dismantling process of waste lithium iron phosphate soft-pack batteries and cylindrical batteries.

[0075] This embodiment:

[0076] The three sets of nozzles 77 adopt a vertical layered layout, combined with the fan-shaped spray coverage formed by synchronous rotation, which can cover all reaction areas inside the production tank 2 in an all-round and dead-angle manner, greatly expanding the spray coverage area of ​​deionized water. During the water injection process, the water flow falls evenly in a fan-shaped diffused manner, which can wet and disperse the lithium iron phosphate cathode powder in the tank layer by layer, avoiding the problems of cathode powder accumulation, agglomeration and clumping from the root, ensuring that each cathode powder particle can quickly and fully contact and wet with deionized water, laying a uniform solid-liquid system foundation for the subsequent catalytic oxidation leaching reaction;

[0077] This process aims to achieve closed-loop recycling of renewable solid waste such as waste lithium iron phosphate, while ensuring a stable production of high-quality battery-grade lithium carbonate. In terms of solid waste recycling, this process uses iron single-atom catalytic advanced oxidation selective leaching technology, which can efficiently separate and extract lithium from waste lithium iron phosphate solid waste. The iron and phosphorus components are completely recovered in the form of iron phosphate solid residue, realizing the resource utilization of all components of solid waste.

[0078] Second embodiment:

[0079] Please see Figure 7 It also includes a material distribution mechanism 8;

[0080] The material distribution mechanism 8 includes a positioning plate 81 fixed to the inner wall of the transmission ring 712, and a reciprocating rotating material distribution plate 82 integrally provided on the outer wall of the positioning plate 81.

[0081] The material distribution plate 82 is directly opposite the outlet of the discharge pipe 93, and the material distribution plate 82 is eccentrically positioned about the axis of the transmission ring 712.

[0082] Please see Figure 7 (c) In the first embodiment, when the transmission ring 712 is in the initial state, the position of the material distribution plate 82 is vertical, and the positive electrode powder falling through the discharge pipe 93 will fall directly onto the material distribution plate 82.

[0083] Please see Figure 7 In (d): During the operation of the first embodiment, when the transmission ring 712 reciprocates in both directions, the transmission ring 712 will synchronously control the positioning plate 81 to make the material distribution plate 82 eccentrically reciprocate along the axis of the transmission ring 712. During the rotation, the positive electrode powder falling from the discharge pipe 93 is crushed by patting, and at the same time, it is further oscillated and dispersed into the production tank 2.

[0084] Understandably, compared to traditional designs, the eccentric movement of the material distribution plate 82 helps maintain the optimal dispersion range of the positive electrode powder.

[0085] This embodiment:

[0086] Even after heat treatment, waste lithium iron phosphate cathode powder still exhibits compression and agglomeration, with fine particles clustering together. If directly added to the leaching tank, the material inside the agglomerates is difficult to contact with the aqueous solution and catalyst. This solution uses a synchronous rotating distribution plate 82 to dynamically distribute the cathode powder. The reciprocating rotation can fully break up and disperse the agglomerate cathode powder, ensuring that loose fine particles fall into the production tank 2. Fine powdered cathode material is continuously and evenly sprinkled. Three vertical layered rotating nozzles 77 synchronously output fan-shaped diffused deionized water. As soon as the falling powder enters the tank space, it is immediately enveloped and flushed by multiple layers of fan-shaped water flow, preventing the problem of dry powder floating on the liquid surface and the surface material not being able to fully dissolve in water.

[0087] Third embodiment:

[0088] Please see Figure 6 It also includes auxiliary mechanisms 9;

[0089] A sliding sleeve 11 is slidably installed on the outer wall of the key rod 10. A lifting plate 12 is fixedly installed at the top of the sliding sleeve 11. The auxiliary mechanism 9 includes a sleeve 91 fixed inside the mounting frame 4. A piston 94 is slidably installed inside the sleeve 91. A through hole 95 is opened inside the piston 94. An inlet pipe 92 and an outlet pipe 93 are installed through the two sides of the sleeve 91. A spring rod 96 is fixedly installed at the bottom end of the piston 94. A guide wheel 97 is installed at the bottom end of the spring rod 96.

[0090] The spring rod 96 slides about the sleeve 91 in the vertical direction, the outer wall of the guide wheel 97 and the upper surface of the lifting plate 12 are in contact with each other, and the outlet end of the discharge pipe 93 is located on the upper surface of the material distribution plate 82.

[0091] Please see Figure 6 During the operation of the first and second embodiments, the piston 94 blocks the inlet pipe 92 and the outlet pipe 93. At this time, the user starts the leaching motor 5 to control the mixing rack 13 to rotate, which can only initially mix and leach the deionized water and the positive electrode powder.

[0092] As the leaching process enters the middle stage, the user needs to slide the sliding sleeve 11 to control the lifting plate 12 to rise. The rise of the lifting plate 12 controls the guide wheel 97 to drive the spring rod 96 to control the piston 94 to rise in the sleeve 91. Finally, the through hole 95 enters between the inlet pipe 92 and the outlet pipe 93. At this time, the hydrogen peroxide solution will be discharged through the outlet pipe 93 into the distribution plate 82 and dispersed in the production tank 2.

[0093] This embodiment:

[0094] Hydrogen peroxide solution is sprayed onto the upper surface of the inside of production tank 2. The hydrogen peroxide liquid continuously washes the surface layers, and the adhering powder is peeled off by the fluid scouring force. When the hard agglomerates of the positive electrode powder float on the upper surface of production tank 2, the continuously sprayed hydrogen peroxide solution can fully wet and wrap the agglomerates. The hydrogen peroxide penetrates into the interior of the powder agglomerates, loosening the bonding force between the particles in advance. Large powder agglomerates are quickly dissolved and broken down into fine particles before being dissolved into production tank 2. At the same time, the distribution plate 82 can homogenize the hydrogen peroxide solution into production tank 2.

[0095] The process for recovering battery-grade lithium carbonate from solid waste includes the following steps:

[0096] S1: Preprocessing;

[0097] Waste lithium iron phosphate batteries are discharged and disassembled to obtain positive electrode sheets. The positive electrode sheets are then heat-treated in an inert atmosphere to remove the binder and peel off to obtain lithium iron phosphate positive electrode powder. The heat treatment temperature is 450-550℃, the holding time is 2-4 hours, and the atmosphere is nitrogen or argon.

[0098] S2: Preparation of iron single-atom catalyst;

[0099] Iron salts and nitrogen-containing organic matter are dissolved in deionized water, carbon support is added, ultrasonic dispersion is performed, and the mixture is dried. The dried product is then pyrolyzed at 700-900℃ for 1-3 hours under an inert atmosphere to obtain an iron single-atom catalyst.

[0100] Preferably, the iron salt is ferric nitrate, ferric chloride, or ferric sulfate; the nitrogen-containing organic compound is melamine, dicyandiamine, or polyaniline; and the carbon support is Ketjen black, activated carbon, or carbon nanotubes.

[0101] More preferably, the mass ratio of iron salt to nitrogen-containing organic matter is 1:(5-20), and the mass ratio of iron salt to carbon support is 1:(2-10).

[0102] S3: Advanced oxidative leaching;

[0103] The lithium iron phosphate cathode powder obtained in S1 was dispersed in deionized water with a solid-liquid ratio of (10-50) g / L. The iron single-atom catalyst prepared in S2 was added, and the amount of catalyst was 1%-10% of the mass of lithium iron phosphate.

[0104] Adjust the pH of the solution to 3-6 (using dilute sulfuric acid or dilute hydrochloric acid), and add hydrogen peroxide solution dropwise under stirring. The amount of hydrogen peroxide added is 1-3 times the molar amount of lithium iron phosphate. The reaction temperature is 25-60℃, and the reaction time is 30-120 minutes.

[0105] Leaching must be performed in equipment that utilizes solid waste to recycle battery-grade lithium carbonate.

[0106] During the reaction, the iron single-atom catalyst activates hydrogen peroxide to generate hydroxyl radicals (·OH). These hydroxyl radicals oxidize Fe(II) in lithium iron phosphate to Fe(III), while Li... + The lithium iron phosphate is extracted from the crystal lattice and enters the solution, where it is converted into iron phosphate. After the reaction is complete, the lithium-containing leachate and iron phosphate residue are obtained by filtration.

[0107] S4: Lithium carbonate precipitate;

[0108] The lithium-containing leachate obtained from S3 was concentrated to a lithium ion mass concentration of 15-25 g / L, heated to 80-95℃, and a saturated sodium carbonate solution was slowly added under stirring. The amount of sodium carbonate added was controlled to be 0.55-0.65 times the molar amount of lithium ions. The reaction was kept at this temperature for 1-2 hours, allowed to stand and age, and then filtered to obtain crude lithium carbonate.

[0109] S5: Washing and purification;

[0110] The crude lithium carbonate obtained from S4 is washed with hot water at 80-95℃ for 2-4 times, with a liquid-to-solid ratio of (2-5):1. After drying, battery-grade lithium carbonate is obtained.

[0111] The Fe-N iron single-atom catalyst in this process xThe site can efficiently adsorb and activate hydrogen peroxide, generating hydroxyl radicals (·OH) via a Fenton-like reaction pathway. These hydroxyl radicals possess extremely strong oxidizing power (E°=2.80V), rapidly oxidizing Fe(II) in lithium iron phosphate to Fe(III), thus disrupting the olivine structure of LiFePO4. After the crystal structure is destroyed, lithium is released from the octahedral voids into the solution, while Fe(III) reacts with PO4. 3- A stable iron phosphate precipitate is formed in situ. During the entire reaction process, lithium and iron are selectively separated—lithium enters the liquid phase, while iron remains in the solid phase as FePO4.

[0112] Compared to traditional direct oxidation by hydrogen peroxide, the hydroxyl radicals generated by iron single-atom catalytic activation have a faster reaction rate and stronger oxidation capacity, enabling rapid oxidation of lithium iron phosphate under mild conditions, and the catalyst can be recycled.

[0113] Please refer to the reference again. Figures 1 to 7 The working principle of the battery-grade lithium carbonate recycling equipment and recycling process provided by this invention is as follows:

[0114] In step S1, during leaching, the user starts the injection motor 72 to drive the first pulley 73 to rotate. When the first pulley 73 rotates, the transmission timing belt 76 controls the double groove pulley 74 and the second pulley 75 to rotate synchronously in the same direction. The first pulley 73, the double groove pulley 74 and the second pulley 75 drive the corresponding first drive wheel 78, the second drive wheel 79 and the third drive wheel 710 to rotate under the force of the transmission ring 712. During the rotation of the transmission ring 712, it drives the two driven wheels 711 to rotate synchronously, thereby controlling the spray range of the three nozzles 77 facing outward to rotate from the initial outer side to the inner side to spray deionized water.

[0115] In step S2, when the transmission ring 712 reciprocates in both forward and reverse directions, the transmission ring 712 will synchronously control the positioning plate 81 to make the material distribution plate 82 eccentrically reciprocate along the axis of the transmission ring 712. During the rotation, the positive electrode powder falling from the discharge pipe 93 is crushed by patting, and at the same time, it is further oscillated and dispersed into the production tank 2.

[0116] Step S3: Start the leaching motor 5 to control the key lever 10 to rotate. The key lever 10 can control the mixing rack 13 to rotate inside the production tank 2, thereby fully mixing and leaching the waste lithium iron phosphate cathode powder and deionized water inside the production tank 2.

[0117] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A device for recycling battery-grade lithium carbonate from solid waste, characterized in that, Includes the support frame, production tank, and injection mechanism; The production tank is located in the middle of the inside of the support frame. A top cover is fixedly installed on the top of the production tank. A top plate is fixedly installed on the upper surface of the top cover. An installation frame is fixedly installed on the upper surface of the top plate. An leaching motor is installed on the top of the installation frame. A key rod is connected to the output shaft of the leaching motor via a keyway. A mixing frame is fixedly installed at the bottom of the key rod inside the production tank. The injection mechanism includes a positioning frame mounted on the upper surface of the top cover and located on one side of the mounting bracket. An injection motor is mounted on the top of the positioning frame. The output shaft of the injection motor is connected to a first pulley via a keyway. A double-groove pulley and a second pulley are rotatably mounted inside the top cover and on one side of the first pulley. A synchronous belt is sleeved on the outer wall of the first pulley, the double-groove pulley, and the second pulley. The first pulley, the double-groove pulley, and the second pulley are respectively keyway connected to the first drive wheel, the second drive wheel, and the third drive wheel at their shaft centers and below the top cover; The injection mechanism also includes two driven wheels, with nozzles installed at the shaft centers of the two driven wheels and the shaft center of the second drive wheel, and a transmission ring rotatably connected at the center of the top cover.

2. The equipment for recycling battery-grade lithium carbonate from solid waste according to claim 1, characterized in that, The first drive wheel, the second drive wheel, and the third drive wheel are in close contact with the outer walls of the two driven wheels and the inner wall of the transmission ring.

3. The equipment for recycling battery-grade lithium carbonate from solid waste according to claim 1, characterized in that, The first drive wheel, the second drive wheel, and the third drive wheel are equidistantly distributed in a ring with the two driven wheels about the axis of the transmission ring.

4. The equipment for recycling battery-grade lithium carbonate from solid waste according to claim 1, characterized in that, It also includes a material distribution mechanism; The material distribution mechanism includes a positioning plate fixed to the inner wall of the transmission ring, and a reciprocating rotating material distribution plate is integrally provided on the outer wall of the positioning plate.

5. The equipment for recycling battery-grade lithium carbonate from solid waste according to claim 4, characterized in that, The material distribution plate is directly opposite the outlet of the discharge pipe, and the material distribution plate is eccentrically positioned about the axis of the transmission ring.

6. The equipment for recycling battery-grade lithium carbonate from solid waste according to claim 1, characterized in that, It also includes auxiliary mechanisms; A sliding sleeve is slidably installed on the outer wall of the key rod, and a lifting plate is fixedly installed at the top of the sliding sleeve. The auxiliary mechanism includes a sleeve fixed inside the mounting frame, a piston slidably installed inside the sleeve, a through hole opened inside the piston, an inlet pipe and an outlet pipe installed through both sides of the sleeve, a spring rod fixedly installed at the bottom end of the piston, and a guide wheel installed at the bottom end of the spring rod.

7. The equipment for recovering battery-grade lithium carbonate from solid waste according to claim 6, characterized in that, The spring rod slides about the sleeve in the vertical direction, the outer wall of the guide wheel and the upper surface of the lifting plate are in contact with each other, and the outlet end of the discharge pipe is located on the upper surface of the material distribution plate.

8. A process for recovering battery-grade lithium carbonate from solid waste, characterized in that, Includes the following steps: S1: Preprocessing; Waste lithium iron phosphate batteries are discharged and disassembled to obtain positive electrode sheets. The positive electrode sheets are then heat-treated in an inert atmosphere to remove the binder and peeled off to obtain lithium iron phosphate positive electrode powder. S2: Preparation of iron single-atom catalyst; Iron salts and nitrogen-containing organic matter were dissolved in deionized water, carbon support was added, the mixture was ultrasonically dispersed and dried, and the dried product was pyrolyzed under an inert atmosphere to obtain an iron single-atom catalyst. S3: Advanced oxidative leaching; The lithium iron phosphate cathode powder obtained in S1 was dispersed in deionized water, and the iron single-atom catalyst prepared in S2 was added. Adjust the pH of the solution and add hydrogen peroxide solution dropwise under stirring to fully leach out the solution; The leaching process must be performed in the equipment for recycling battery-grade lithium carbonate from solid waste as described in any one of claims 1-7; S4: Lithium carbonate precipitate; The lithium-containing leachate obtained from S3 was concentrated, and a saturated sodium carbonate solution was slowly added under stirring. After standing and aging, crude lithium carbonate was obtained by filtration. S5: Washing and purification; The crude lithium carbonate obtained from S4 was washed with hot water and dried to obtain battery-grade lithium carbonate product.

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