Comprehensive utilization method of waste lithium iron phosphate battery

Abstract

The invention belongs to the technical field of battery recovery, and particularly relates to a method for comprehensively utilizing waste lithium iron phosphate batteries, which comprises the following steps: crushing and pyrolyzing: carrying out charged crushing on the charged waste lithium iron phosphate batteries through a crushing device to obtain a crushed mixture, and carrying out anaerobic pyrolysis on the crushed mixture through a pyrolyzing furnace to obtain the waste lithium iron phosphate batteries. Removing organic matters to obtain a crushed battery; screening and stripping: screening and stripping the crushed battery to obtain a copper foil, an aluminum foil and positive and negative electrode black powder; pulping and flotation: adding a flotation agent into the anode and cathode black powder, and stirring to obtain mixed slurry; through recycling, mechanical application, harmless treatment and other processes, the resource utilization rate is increased, the environment is prevented from being destroyed by pollutants, the operation cost is also saved, meanwhile, the spoiler and the blocking liquid are arranged in the feeding cavity, and the situation that when the battery cells are fed, the blocking liquid is blocked is avoided. And gas outside the device enters the crusher main body, so that the oxygen content in the crusher main body is changed.

Description

Technical Field

[0001] The invention belongs to the technical field of battery recycling, and in particular relates to a method for comprehensive utilization of waste lithium iron phosphate batteries. Background Art

[0002] With the rapid development of new energy vehicles and renewable energy storage systems, lithium iron phosphate batteries have been widely used as an efficient and environmentally friendly energy storage device. However, with the end of the service life of these batteries, how to effectively recycle and reuse spent lithium iron phosphate batteries has become an urgent problem to be solved. Currently, there are various methods for the treatment of spent batteries, but there are generally problems such as low resource utilization, high operating costs, and secondary pollution to the environment. Therefore, it is particularly important to develop a method that can efficiently, safely and environmentally friendly treat spent lithium iron phosphate batteries.

[0003] When recycling waste lithium iron phosphate batteries, they usually need to be physically crushed first to facilitate subsequent chemical treatment or material separation. However, due to the residual electrical energy inside the battery, direct crushing poses a great safety hazard, especially when the air outside the device enters the confined space during the crushing process, it may cause explosions or sparks and other safety accidents due to changes in oxygen content. In addition, existing live crushing technology and equipment often cannot effectively avoid this problem, thus limiting its scope of application in industry.

[0004] In response to the above problems, this application document proposes a method for comprehensive utilization of waste lithium iron phosphate batteries to improve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a method for comprehensive utilization of waste lithium iron phosphate batteries. Through recycling, application, harmless treatment and other process treatments, the resource utilization rate is improved, the damage to the environment by pollutants is avoided, and the operating cost is saved. At the same time, by arranging a baffle and a plugging liquid inside the feeding chamber, it is avoided that when the battery cell is added, the gas outside the device enters the inside of the crusher body and causes the oxygen content inside the crusher body to change.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for comprehensive utilization of waste lithium iron phosphate batteries, comprising the following steps:

[0008] Stp1: crushing and pyrolysis, using a crushing device to crush the charged waste lithium iron phosphate batteries to obtain a crushed mixture, and then using a pyrolysis furnace to perform oxygen-free pyrolysis on the crushed mixture to remove organic matter and obtain battery crushed products;

[0009] Stp2: Screening and stripping: Screening and stripping the battery crushed materials to obtain copper foil, aluminum foil and positive and negative electrode black powder;

[0010] Stp3: slurry flotation, adding flotation agent to the positive and negative electrode black powders, stirring to obtain a mixed slurry, and purifying the mixed slurry by flotation to obtain the positive electrode material;

[0011] Stp4: Leaching, leaching the positive electrode material with inorganic strong acid and strong oxidant, filtering, and obtaining iron phosphate and leaching mother liquor;

[0012] Stp5: Purification: adding a purifying agent to the leaching mother liquor to remove metal ions, and then concentrating it to obtain a leachate;

[0013] Stp6: evaporation and concentration, evaporating and concentrating the leaching solution to obtain a concentrated leaching solution;

[0014] Stp7: electrolysis, electrolyzing the concentrated leachate to obtain oxygen, hydrogen, sulfuric acid and leachate;

[0015] Step 8: lithium precipitation and washing, adding carbon dioxide and a precipitant to the leaching filtrate to precipitate lithium to obtain lithium carbonate precipitate, and washing the lithium carbonate precipitate to obtain lithium hydroxide;

[0016] Stp9: Drying and packaging, drying the lithium hydroxide to obtain the finished lithium hydroxide product, and packaging the finished lithium hydroxide product.

[0017] In a preferred embodiment, in Stp1, during the charged crushing, the oxygen content inside the crushing device is ≤3%, the rotation speed of the crushing blade shaft is 80-140 r / min, and the temperature of anaerobic pyrolysis is 500°C.

[0018] In a preferred embodiment, in Stp2, the crushed mixture after pyrolysis is screened and peeled, comprising the following steps:

[0019] S21: Screening the crushed mixture after pyrolysis through a first square swing screen to obtain a first separated product and black powder;

[0020] S22: crushing the first separated material by a first hammer crushing device to obtain a first crushed material;

[0021] S23: Screening the first crushed product through a second square swing screen to obtain a second separated product and black powder;

[0022] S24: crushing the second separated material by a second hammer crushing device to obtain a second crushed material;

[0023] S25: Screening the second crushed product through a circular swing screen to obtain a third separated product and black powder;

[0024] S26: grinding the third separated product by a grinding device to obtain a first ground product;

[0025] S27: Screening the first ground material through a vibrating screen to obtain copper particles, aluminum particles and black powder;

[0026] S28: Collect the black powder obtained in S21 to S27.

[0027] In a preferred embodiment, in S22, the particle size of the first crushed material is ≤10 mm; in S24, the particle size of the second crushed material is ≤3 mm; in S26, the particle size of the first ground material is ≤1 mm.

[0028] In a preferred embodiment, in Stp7, oxygen and sulfuric acid obtained by electrolysis are used in the leaching step.

[0029] In a preferred embodiment, in Stp1, the steps before the charged waste lithium iron phosphate battery is crushed by the crushing device also include:

[0030] Discharging used lithium iron phosphate batteries through salt water;

[0031] Drying the discharged waste lithium iron phosphate batteries through drying equipment;

[0032] Among them, the voltage of the used lithium iron phosphate battery after discharge is ≤3V.

[0033] In a preferred embodiment, in Step 1, the crushing device includes a crusher body, nitrogen is injected into the crusher body, a crushing module is integrated into the crusher body, and the crushing module can crush the battery cell, and further includes:

[0034] A feeding part, the feeding part is assembled at the input end of the crusher body, the feeding part comprises a shell and a baffle, the shell is fixed to the input end of the crusher body, a feeding chamber and a liquid storage chamber are sequentially provided inside the shell from the lower end to the upper end, an air chamber is provided at one end of the liquid storage chamber close to the crusher body, a liquid injection pipe is provided at the upper end of the air chamber, a water pump is fixed at the upper end of the air chamber, the input end of the water pump and the liquid storage chamber, as well as the output end of the water pump and the feeding chamber are connected by pipelines, a plurality of air inlets and a plurality of air outlets are evenly provided at one end of the air chamber close to the crusher body, and the baffle is fixed to the upper end of the feeding chamber;

[0035] A conveying part, which is assembled inside the feeding cavity and can convey the battery cells inside the shell to the inside of the crusher body;

[0036] A drying part, which is installed inside the feeding chamber and can dry the battery cells;

[0037] The cross-sectional shape of the feeding cavity is V-shaped, a plugging liquid is injected into the lower end of the feeding cavity, and the lower end of the baffle is immersed in the plugging liquid.

[0038] In a preferred embodiment, the conveying part includes a motor, a driving roller, a driven roller and a climbing conveyor belt, the motor is fixed to one side of the shell, the driving roller and the driven roller are both rotatably connected to the inside of the shell, and the driving roller and the output end of the motor are fixedly connected, the climbing conveyor belt is assembled on the outside of the driving roller and the driven roller, a plurality of belt troughs are evenly opened on the outside of the climbing conveyor belt, a plurality of drainage holes are evenly opened inside the belt trough, wherein the lower ends of the driven roller and the climbing conveyor belt are immersed in the plugging liquid.

[0039] In a preferred embodiment, the drying section includes multiple heating wires and multiple fans, the multiple heating wires are all installed inside the wind cavity, the fans are all fixed to one end of the wind cavity close to the crusher body, and the multiple fans and multiple air outlets are matched one by one.

[0040] In a preferred embodiment, a liquid level sensor and a temperature sensor are fixed inside the shell, and the liquid level sensor is located at the lower end of the liquid storage cavity.

[0041] The technical effects achieved by the present invention are:

[0042] The present invention performs charged crushing and oxygen-free pyrolysis in a protective gas, thereby avoiding the environmental pollution problem caused by electrolyte leakage. Through recycling, application, harmless treatment and other process treatments, the pollutants generated in the process of recycling waste lithium iron phosphate batteries are treated and recycled, thereby improving resource utilization, avoiding environmental damage caused by pollutants, and saving operating costs.

[0043] When the waste battery is crushed and pyrolyzed, the present invention arranges a shell at the input end of the crusher body, injects a plugging liquid into the shell, and separates the inside of the feeding chamber by the cooperation of the plugging liquid and the baffle plate, thereby preventing the gas outside the device from entering the crusher body when the battery cell is put into the device, avoiding the change of the oxygen content inside the crusher body, eliminating the potential safety hazard caused by the change of oxygen content, and improving the safety performance of the device;

[0044] When the present invention crushes and pyrolyzes waste batteries, after the motor is running, in the process of transporting the battery core to the inside of the crusher body through the climbing conveyor belt, the surface of the battery core can be dried through the cooperation of the heating wire and the fan, so as to prevent the residual liquid on the surface of the battery core from entering the subsequent processing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a process flow chart of the present invention as a whole;

[0046] Figure 2 It is a schematic diagram of the overall structure of the crushing device of the present invention;

[0047] Figure 3 It is a rear view of the structure of the crushing device of the present invention;

[0048] Figure 4 It is a structural schematic diagram of the feeding part of the present invention;

[0049] Figure 5 It is a structural cross-sectional view of the feeding part of the present invention;

[0050] Figure 6 It is a structural schematic diagram of the conveying part of the present invention;

[0051] Figure 7 It is a schematic diagram of the movement path of the battery cell of the present invention inside the shell.

[0052] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0053] 10. Crusher body; 20. Feeding part; 21. Shell; 22. Baffle; 23. Feeding chamber; 24. Liquid storage chamber; 25. Wind chamber; 26. Liquid injection pipe; 27. Water pump; 28. Liquid level sensor; 29. ​​Temperature sensor; 30. Conveying part; 31. Motor; 32. Active roller; 33. Driven roller; 34. Climbing conveyor belt; 35. Belt trough; 36. Drain hole; 40. Drying part; 41. Heating wire; 42. Fan. DETAILED DESCRIPTION

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0056] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The phrase "in a preferred embodiment" that appears in different places in this specification does not refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0057] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0058] Please refer to the attached Figure 1 As shown, it is the first embodiment of the present invention, which provides a method for comprehensive utilization of waste lithium iron phosphate batteries, including the following steps:

[0059] Stp1: crushing and pyrolysis, soaking the waste lithium iron phosphate battery in salt water for 72h to 96h to discharge, so that the voltage of the waste lithium iron phosphate battery is ≤3V, and then the discharged waste lithium iron phosphate battery is dried by drying equipment; the protective gas is filled into the crushing device, so that the oxygen content inside the crushing device is ≤3%. Under the protection of the protective gas, the charged waste lithium iron phosphate battery is crushed by the crushing device, and the speed of the crushing blade shaft is 80 to 140r / min to obtain a crushed mixture containing solid crushed materials and electrolyte, and then the crushed mixture is subjected to anaerobic pyrolysis by a pyrolysis furnace to remove organic matter. The temperature of anaerobic pyrolysis is 500℃ to obtain battery crushed materials and waste gas, wherein the waste gas is treated by the tail gas treatment system and discharged after meeting the standards;

[0060] Here, charged crushing is carried out in nitrogen protection, which avoids the environmental pollution problems of traditional crushing after discharge, long process cycle, and leakage of electrolyte from damaged batteries, thereby realizing environmentally friendly and efficient production. Compared with the "shredder + multiple crushing" process in the prior art, charged crushing in protective gas can achieve uniform particle size of the crushed mixture, loose materials, and no wrapping phenomenon, thereby reducing the doping of copper chips and aluminum chips in the pole powder; at the same time, organic impurities present in the crushed mixture can be effectively removed through anaerobic pyrolysis, and organic matter such as binder, residual diaphragm paper and electrolyte can be pyrolyzed under high temperature and anaerobic conditions, thereby realizing pollution-free treatment.

[0061] Stp2: Screening and stripping, the battery crushed materials are screened and stripped by a screening system in a multi-component screening and sorting manner to obtain copper foil, aluminum foil, positive and negative electrode black powder, stainless steel shell, iron, pile head, etc.

[0062] Furthermore, the screening system is also equipped with a full negative pressure powder collection system and a metal sorting system. The full negative pressure powder collection system can collect the positive and negative electrode black powder that is screened and peeled off, and the metal sorting system can collect and screen copper foil, aluminum foil, stainless steel shell, iron, and pile heads.

[0063] Here, through multi-component screening and sorting, organic matter in waste lithium iron phosphate batteries is removed, the fluorine content is effectively degraded, and the positive and negative electrode black powder active substances are detached from the current collector, so as to achieve efficient extraction and reuse of valuable components, reduce environmental pollution, and promote the recycling of resources;

[0064] Stp3: slurry flotation, adding flotation agent to the positive and negative electrode black powder, stirring to obtain a mixed slurry, purifying the mixed slurry by flotation method, removing the negative electrode material, and obtaining the positive electrode material containing lithium iron phosphate;

[0065] Here, the flotation agent includes a collector, a pH regulator, a dispersant and a foaming agent. In this embodiment, the collector is preferably emulsified diesel, the pH regulator is preferably sodium hydroxide, the dispersant is preferably sodium hexametaphosphate, and the foaming agent is preferably MIBC oil;

[0066] Among them, the graphite has natural floatability and is purified through flotation process to increase the graphite quality to 80% to 95%;

[0067] Stp4: Leaching, leaching the positive electrode material with an inorganic strong acid and a strong oxidant, filtering, and obtaining acid leaching residue containing iron phosphate and leaching mother liquor, wherein the waste gas generated during the leaching process is connected to the tail gas treatment system, and the acid leaching residue containing iron phosphate is harmlessly treated;

[0068] Furthermore, during the harmless treatment of the acid leaching residue, aluminum is removed by ball milling and alkalization. After aluminum removal, diammonium phosphate solution, hydrogen peroxide and soda ash solution are added in a reactor to synthesize iron phosphate slurry. The slurry is aged and then filtered and washed. The washed iron phosphate is flash dried. The flash dried iron phosphate is then dried in a rotary kiln to remove crystal water. Finally, it is pulverized by air flow and packaged to obtain a battery-grade iron phosphate product. This technology achieves complete harmless disposal of iron phosphate and graphite, reaches the leading level in the domestic industry, realizes the goal of full resource recycling, and responds to the country's call for green development.

[0069] Stp5: Purification, adding a purifying agent to the leaching mother liquor to remove metal ions (such as copper, iron, aluminum, fluorine, phosphorus, calcium, magnesium and other metal ions), and then concentrating and separating to obtain a leaching solution and purified slag, wherein the purified slag is harmlessly treated;

[0070] Stp6: Evaporation and concentration: evaporate and concentrate the leaching solution to increase the lithium concentration in the leaching solution and obtain a concentrated leaching solution;

[0071] Stp7: electrolysis, the concentrated leachate is electrolyzed by a bipolar membrane electrolyzer (the structure is bipolar two-membrane three-chamber) to obtain hydrogen, oxygen, sulfuric acid and leachate, among which oxygen and sulfuric acid are used in Stp4, and hydrogen is recovered;

[0072] Specifically, the concentrated leachate is added to the anode chamber of the bipolar membrane electrolyzer, and a lithium hydroxide solution with a concentration of 6% is added to the cathode chamber, the cathode plate and the cation exchange membrane are adjusted so that the pressure on the cathode side of the cation exchange membrane is higher than the pressure on the anode side, and then the temperature of the solution in the anode chamber and the cathode chamber is adjusted to 60° C. to 80° C., sulfuric acid is added to the anode chamber, and the pH value of the solution in the anode chamber is adjusted to pH 2.0 to 3.5, and current is passed through the electrolyzer, and the cell voltage and current density of the bipolar membrane electrolyzer are regulated so that the voltage of the electrolyzer is between 3V and 5V, and the current density is 1.5 to 2.0 kA / m 2 , and then electrolysis begins. Under the action of the electric field force, the lithium ions in the anode chamber gradually move toward the ion exchange membrane and pass through the ion exchange membrane, migrating from the anode chamber to the cathode chamber. The lithium ions entering the cathode chamber combine with the hydroxide ions to generate hydrogen and a leaching solution containing lithium hydroxide. The sulfuric acid and oxygen produced by the anode can be recycled to the leaching step (step 4). Through this scheme, almost no pollutants are generated during the electrolysis process, and the recycling of the products in the entire electrolysis process is realized, thereby saving production costs;

[0073] Stp8: lithium precipitation and washing, adding carbon dioxide and a precipitant to the leaching filtrate to precipitate lithium to obtain a lithium carbonate precipitate, and washing the lithium carbonate precipitate with ultrapurified water for 3 times at room temperature to obtain lithium hydroxide, wherein the volume ratio of the lithium carbonate precipitate to the ultrapurified water is 1:2;

[0074] Stp9: Drying and packaging, drying the lithium hydroxide to obtain the finished lithium hydroxide product, and packaging the finished lithium hydroxide product.

[0075] It should be noted that in Stp1, the protective gas is preferably nitrogen, in Stp4, the inorganic strong acid is preferably sulfuric acid, the strong oxidant is preferably hydrogen peroxide, and in Stp8, the precipitant is preferably sodium carbonate.

[0076] In this embodiment, through the above-mentioned scheme setting, in the process of recycling waste lithium iron phosphate batteries, charged crushing is carried out in a protective gas, thereby avoiding the traditional crushing after discharge, the long process cycle, and the environmental pollution problems of electrolyte leakage of damaged batteries. Through anaerobic pyrolysis, the binder, diaphragm paper and other organic matter are fully cracked, and then the positive and negative electrode black powders are peeled off, thereby improving the purity and quality of the positive and negative electrode black powders. Compared with the prior art, the technical scheme treats and recycles the pollutants generated in the process of recycling waste lithium iron phosphate batteries through recycling, application, harmless treatment and other process treatments, thereby improving resource utilization, avoiding pollutants from damaging the environment, achieving pollution-free and no generation of three wastes, saving 15% of operating costs, and significantly improving market competitiveness.

[0077] In a preferred embodiment, in Stp2, the multi-component screening and sorting process comprises the following steps:

[0078] S21: Screening the crushed mixture after pyrolysis through a first square swing screen to obtain a first separated product and positive and negative electrode black powder;

[0079] S22: crushing the first separated material by a first hammer crushing device to obtain a first crushed material, wherein the particle size of the first crushed material is ≤10 mm;

[0080] S23: Screening the first crushed product through a second square swing screen to obtain a second separated product and positive and negative electrode black powder;

[0081] S24: crushing the second separated product by a second hammer crushing device to obtain a second crushed product, wherein the particle size of the second crushed product is ≤3 mm;

[0082] S25: Screening the second crushed product through a circular swing screen to obtain a third separated product and positive and negative electrode black powder;

[0083] S26: grinding the third separated product by a grinding device to obtain a first ground product, wherein the particle size of the first ground product is ≤1 mm;

[0084] S27: Screening the first ground material through a vibrating screen to obtain copper particles, aluminum particles, and positive and negative electrode black powder;

[0085] S28: collecting the black powder obtained from S21 to S27;

[0086] Among them, through a multi-component screening and sorting process, organic matter in waste lithium iron phosphate batteries is removed, the fluorine content is effectively degraded, and the positive and negative electrode black powders are removed from the current collectors, so that valuable components can be efficiently extracted and reused, environmental pollution can be reduced, resource recycling can be promoted, and the purity and quality of the positive and negative electrode black powders are improved, making the recovery rate of the positive and negative electrode black powders as high as 95%.

[0087] Please refer again Figures 2 to 5 As shown, in Step 1, the crushing device includes a crusher body 10, nitrogen is injected into the crusher body 10, a crushing module is integrated into the crusher body 10, and the crushing module can crush the battery cell, and also includes:

[0088] A feeding part 20 is assembled at the input end of the crusher body 10. The feeding part 20 includes a shell 21 and a baffle 22. The shell 21 is fixed to the input end of the crusher body 10. A feeding chamber 23 and a liquid storage chamber 24 are sequentially provided inside the shell 21 from the lower end to the upper end. An air chamber 25 is provided at one end of the liquid storage chamber 24 close to the crusher body 10. A liquid injection pipe 26 is provided at the upper end of the air chamber 25. A water pump 27 is fixed at the upper end of the air chamber 25. The input end of the water pump 27 and the liquid storage chamber 24 as well as the output end of the water pump 27 and the feeding chamber 23 are connected by pipelines. A plurality of air inlets and a plurality of air outlets are evenly provided at one end of the air chamber 25 close to the crusher body 10. The baffle 22 is fixed to the upper end of the feeding chamber 23.

[0089] The conveying part 30 is assembled inside the feeding cavity 23, and the conveying part 30 can convey the battery cells inside the shell 21 to the inside of the crusher body 10;

[0090] A drying unit 40, which is installed inside the feeding chamber 23 and can dry the battery cells;

[0091] The cross-sectional shape of the feeding cavity 23 is V-shaped, and the lower end of the feeding cavity 23 is injected with a plugging liquid, and the lower end of the baffle 22 and the lower end of the conveying part 30 are immersed in the plugging liquid.

[0092] Specifically, in this embodiment, the plugging fluid is preferably water.

[0093] Here, a conveying module is used in conjunction with the device. The conveying module is connected to the output end of the crusher body 10, and the conveying module can convey the crushed mixture to the next processing equipment.

[0094] It should be noted that the crushing device in this embodiment is mainly aimed at lithium iron phosphate battery packs composed of multiple battery cells (similar to dry batteries). Of course, when recycling battery-type batteries, adaptive adjustments can be made on the basis of this device to suit block batteries with larger volume and weight.

[0095] In this embodiment, when the waste lithium iron phosphate battery (i.e., the battery cell) is charged and crushed, an appropriate amount of plugging liquid is injected into the liquid storage chamber 24 through the liquid injection pipe 26, and the water pump 27 is started. The plugging liquid in the liquid storage chamber 24 is transported to the feeding chamber 23 through the water pump 27, so that the lower end of the baffle plate 22 is immersed in the plugging liquid, and the inside of the feeding chamber 23 is separated by the plugging liquid. Nitrogen is injected into the crusher body 10 so that the oxygen content in the crusher body 10 is ≤3%, and the battery cell is put into the feeding chamber 23 and falls onto the surface of the conveying part 30, and the conveying part 30 is started. The battery cells are driven to move toward the crusher body 10 by the conveying section 30, and the drying section 40 is started to dry the plugging liquid on the surface of the battery cells, and the battery cells are conveyed to the crusher body 10 by the conveying section 30 for charged crushing. When the battery cells are fed into the feeding chamber 23, the gas outside the device cannot enter the crusher body 10 through the feeding chamber 23 due to the isolation of the plugging liquid, thereby avoiding the change of the oxygen content inside the crusher body 10 during the feeding of the battery cells, eliminating the safety hazard caused by the change of oxygen content during the charged crushing process, and improving the safety performance of the device.

[0096] Please refer again Figure 5 The conveying part 30 includes a motor 31, a driving roller 32, a driven roller 33 and a climbing conveyor belt 34. The motor 31 is fixed to one side of the shell 21. The driving roller 32 and the driven roller 33 are rotatably connected to the inside of the shell 21 through sealed bearings, and the driving roller 32 and the output end of the motor 31 are fixedly connected. The climbing conveyor belt 34 is assembled on the outside of the driving roller 32 and the driven roller 33. A plurality of material troughs 35 are evenly opened on the outside of the climbing conveyor belt 34, and a plurality of drainage holes 36 are evenly opened inside the material troughs 35. The lower ends of the driven roller 33 and the climbing conveyor belt 34 are immersed in the plugging liquid.

[0097] In this embodiment, after the battery cells are fed into the sealing liquid in the feeding chamber 23, the battery cells fall onto the surface of the climbing conveyor belt 34, and are limited by the belt trough 35. The motor 31 is started, and the active roller 32 and the climbing conveyor belt 34 are driven to rotate by the motor 31, and the battery cells are driven by the climbing conveyor belt 34 to move toward the input end of the crusher body 10. When the battery cells are separated from the sealing liquid, the residual sealing liquid on the surface of the battery cells flows back to the feeding chamber 23 through the drain hole 36, and the drying section 40 is started to dry the surface of the battery cells. The sealing liquid forms a partition inside the feeding chamber 23 to prevent air outside the device from entering the crusher body 10, and the battery cells are transported to the crusher body 10 through the conveying section 30 for charged crushing.

[0098] Please refer again Figure 4The drying section 40 includes a plurality of heating wires 41 and a plurality of fans 42. The plurality of heating wires 41 are all assembled inside the air cavity 25. The fans 42 are all fixed to one end of the air cavity 25 close to the crusher body 10, and the plurality of fans 42 are matched with the plurality of air outlets one by one.

[0099] In this embodiment, the conveying part 30 is started to convey the battery cells in the plugging liquid to the inside of the crusher body 10. During this process, when the battery cells are separated from the plugging liquid, the fan 42 is started to drive the gas inside the feeding chamber 23 to circulate. At the same time, the heating wire 41 is started to heat the flowing gas by the heating wire 41, thereby increasing the evaporation rate of the plugging liquid on the surface of the battery cells, improving the drying efficiency, and preventing the residual liquid on the surface of the battery cells from entering the subsequent processing equipment.

[0100] Please refer again Figure 4 A liquid level sensor 28 and a temperature sensor 29 are fixed inside the shell 21 , and the liquid level sensor 28 is located at the lower end of the liquid storage chamber 24 . The liquid level sensor 28 is adapted to the plugging liquid inside the shell 21 .

[0101] In this embodiment, with the operation of the heating wire 41 and the fan 42, the blocking liquid will gradually decrease. The setting of the liquid level sensor 28 can monitor the liquid level of the blocking liquid inside the feeding chamber 23. When the liquid level of the blocking liquid inside the feeding chamber 23 is low, the water pump 27 is started, and the blocking liquid inside the liquid storage chamber 24 is transported to the feeding chamber 23 by the water pump 27 to replenish the blocking liquid inside the feeding chamber 23, thereby ensuring the liquid level of the blocking liquid inside the feeding chamber 23 and avoiding the separation of the baffle 22 and the blocking liquid due to the lowering of the blocking liquid level inside the feeding chamber 23, thereby causing the gas outside the device to enter the crusher body 10 and causing the oxygen content inside the crusher body 10 to change. At the same time, the setting of the temperature sensor 29 can monitor the temperature inside the feeding chamber 23 to avoid the temperature inside the feeding chamber 23 being too high.

[0102] The above are only preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to conventional means in the art unless otherwise specified and limited.

Claims

1. A method for comprehensive utilization of waste lithium iron phosphate batteries, characterized in that: The following steps are involved: Stp1: crushing and pyrolysis, using a crushing device to crush the charged waste lithium iron phosphate batteries to obtain a crushed mixture, and then using a pyrolysis furnace to perform oxygen-free pyrolysis on the crushed mixture to remove organic matter and obtain battery crushed products; Stp2: Screening and stripping: Screening and stripping the battery crushed materials to obtain copper foil, aluminum foil and positive and negative electrode black powder; Stp3: slurry flotation, adding flotation agent to the positive and negative electrode black powders, stirring to obtain a mixed slurry, and purifying the mixed slurry by flotation to obtain the positive electrode material; Stp4: Leaching, leaching the positive electrode material with inorganic strong acid and strong oxidant, filtering, and obtaining iron phosphate and leaching mother liquor; Stp5: Purification: adding a purifying agent to the leaching mother liquor to remove metal ions, and then concentrating it to obtain a leachate; Stp6: evaporation and concentration, evaporating and concentrating the leaching solution to obtain a concentrated leaching solution; Stp7: electrolysis, electrolyzing the concentrated leachate to obtain oxygen, hydrogen, sulfuric acid and leachate; Step 8: lithium precipitation and washing, adding carbon dioxide and a precipitant to the leaching filtrate to precipitate lithium to obtain lithium carbonate precipitate, and washing the lithium carbonate precipitate to obtain lithium hydroxide; Stp9: Drying and packaging, drying the lithium hydroxide to obtain the finished lithium hydroxide product, and packaging the finished lithium hydroxide product.

2. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 1, characterized in that: In Stp1, during the charged crushing, the oxygen content inside the crushing device is ≤3%, the rotation speed of the crushing blade shaft is 80-140 r / min, and the temperature of the anaerobic pyrolysis is 500°C.

3. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 1, characterized in that: In the step Stp2, the crushed mixture after pyrolysis is screened and peeled, comprising the following steps: S21: Screening the crushed mixture after pyrolysis through a first square swing screen to obtain a first separated product and black powder; S22: crushing the first separated material by a first hammer crushing device to obtain a first crushed material; S23: Screening the first crushed product through a second square swing screen to obtain a second separated product and black powder; S24: crushing the second separated material by a second hammer crushing device to obtain a second crushed material; S25: Screening the second crushed product through a circular swing screen to obtain a third separated product and black powder; S26: grinding the third separated product by a grinding device to obtain a first ground product; S27: Screening the first ground material through a vibrating screen to obtain copper particles, aluminum particles and black powder; S28: Collect the black powder obtained in S21 to S27.

4. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 3, characterized in that: In the S22, the particle size of the first crushed material is ≤10 mm; in the S24, the particle size of the second crushed material is ≤3 mm; in the S26, the particle size of the first ground material is ≤1 mm.

5. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 1, characterized in that: In Stp7, oxygen and sulfuric acid obtained by electrolysis are used in the leaching step.

6. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 1, characterized in that: In the above-mentioned Step 1, the steps before the charged waste lithium iron phosphate battery is crushed by the crushing device include: Discharging used lithium iron phosphate batteries through salt water; Drying the discharged waste lithium iron phosphate batteries through drying equipment; Among them, the voltage of the used lithium iron phosphate battery after discharge is ≤3V.

7. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 1, characterized in that: In the Step 1, the crushing device includes a crusher body, nitrogen is injected into the crusher body, a crushing module is integrated into the crusher body, and the crushing module can crush the battery cell, and further includes: A feeding part, the feeding part is assembled at the input end of the crusher body, the feeding part comprises a shell and a baffle, the shell is fixed to the input end of the crusher body, a feeding chamber and a liquid storage chamber are sequentially provided inside the shell from the lower end to the upper end, an air chamber is provided at one end of the liquid storage chamber close to the crusher body, a liquid injection pipe is provided at the upper end of the air chamber, a water pump is fixed at the upper end of the air chamber, the input end of the water pump and the liquid storage chamber, as well as the output end of the water pump and the feeding chamber are connected by pipelines, a plurality of air inlets and a plurality of air outlets are evenly provided at one end of the air chamber close to the crusher body, and the baffle is fixed to the upper end of the feeding chamber; A conveying part, which is assembled inside the feeding cavity and can convey the battery cells inside the shell to the inside of the crusher body; A drying part, which is installed inside the feeding chamber and can dry the battery cells; The cross-sectional shape of the feeding cavity is V-shaped, a plugging liquid is injected into the lower end of the feeding cavity, and the lower end of the baffle is immersed in the plugging liquid.

8. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 7, characterized in that: The conveying part includes a motor, a driving roller, a driven roller and a climbing conveyor belt, wherein the motor is fixed to one side of a shell, the driving roller and the driven roller are both rotatably connected to the inside of the shell, and the driving roller and the output end of the motor are fixedly connected, the climbing conveyor belt is assembled on the outside of the driving roller and the driven roller, a plurality of belt troughs are evenly opened on the outside of the climbing conveyor belt, a plurality of drainage holes are evenly opened inside the belt trough, wherein the lower ends of the driven roller and the climbing conveyor belt are both immersed in the plugging liquid.

9. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 7, characterized in that: The drying section includes a plurality of heating wires and a plurality of fans, the plurality of heating wires are all assembled inside the wind cavity, the fans are all fixed at one end of the wind cavity close to the crusher body, and the plurality of fans are matched with the plurality of air outlets one by one.

10. The method for comprehensive utilization of waste lithium iron phosphate batteries according to claim 7, characterized in that: A liquid level sensor and a temperature sensor are fixed inside the shell, and the liquid level sensor is located at the lower end of the liquid storage cavity.

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