Recycling method of waste lithium ion electrons

Abstract

The invention discloses a method for recycling waste lithium ion electrons, and belongs to the technical field of lithium battery recycling. By controlling the acid leaching conditions, compared with some traditional leaching methods, lithium resources can be recycled more effectively, waste of resources is reduced, the metal impurities are effectively separated in an alternating magnetic field by utilizing an eddy current separation technology on the basis of the remarkable difference between positive and negative electrode materials and the metal impurities in the aspect of conductivity, and the method is suitable for large-scale industrial production. By reasonably regulating and controlling the rotating speed of the magnetic roller and the feeding speed of the alternating magnetic field, metal impurities such as Al and Cu in positive and negative electrode materials are accurately removed, the purity of a subsequently recycled product is remarkably improved, and the finally obtained lithium phosphate product is higher in quality and better meets the standard of industrial application.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery recycling, and in particular relates to a method for recycling waste lithium ion electrons. Background Art

[0002] With the growing global demand for clean energy and the rapid development of science and technology, lithium-ion batteries have been widely used in many fields such as electric vehicles, mobile communications and energy storage due to their many advantages such as high energy density, long cycle life and no memory effect. In the field of electric vehicles, lithium-ion batteries, as the core power source, have promoted the vigorous development of the new energy vehicle industry and their market share has increased year by year. In mobile communications, various mobile devices such as smartphones and tablets are highly dependent on lithium-ion batteries to meet people's requirements for device endurance and portability. In the field of energy storage, lithium-ion batteries are used in scenarios such as grid peak regulation and distributed energy storage, effectively solving the intermittent problem of renewable energy generation.

[0003] However, with the large-scale application of lithium-ion batteries, the amount of waste has also shown a trend of increasing dramatically year by year. According to relevant statistical data, these waste batteries contain high-value resources such as Co, Li, and graphite. If they are not recycled, it will undoubtedly cause a huge waste of resources. What is more serious is that heavy metals such as cobalt, nickel, etc., as well as harmful chemicals in batteries, once entering the ecosystem, will cause serious pollution to soil, water bodies, and air, threatening human health and ecological balance. Currently, common recycling methods include pyrometallurgical and wet recycling processes, but there are problems such as high energy consumption, serious pollution, and long recycling process. Although the physical recycling method has certain advantages, it also has shortcomings such as low material purity. Therefore, it is of great significance to develop a recycling method that is efficient, environmentally friendly, and can improve resource recovery rate. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention combines physical separation and chemical leaching and precipitation technology to achieve efficient recovery of valuable elements such as lithium in discarded lithium-ion batteries, while reducing environmental pollution and energy consumption.

[0005] In order to achieve the above purpose, the following technical scheme is adopted: The recycling method of the present invention first performs pretreatment, safely disassembles the battery and crushes the positive and negative electrode materials to prepare for subsequent separation and reaction. Then physical separation is performed, and physical methods such as eddy current separation are used to remove metal impurities and improve the purity of the material. Then a leaching treatment is performed, using phosphoric acid under specific conditions to leach lithium from the positive electrode material, and then a lithium phosphate product is obtained through a precipitation step. In each step, the recovery efficiency and product quality are further improved by optimizing the process parameters and equipment.

[0006] The present invention provides a method for recycling waste lithium ion electrons, which specifically comprises the following steps:

[0007] S1: pretreatment step, disassembling the discarded lithium-ion batteries after discharge, separating the positive and negative electrode materials, separators and electrolytes, and crushing the positive and negative electrode materials;

[0008] S2: physical separation step, using a physical separation method to preliminarily separate the crushed positive and negative electrode materials to remove metal impurities therein;

[0009] S3: Leaching treatment step, using phosphoric acid to leach the positive electrode material after preliminary separation, controlling the phosphoric acid concentration to 3.41 mol / L, the solid-liquid ratio to 1:5, and leaching for 3 hours at a stirring speed of 500 r / min and a water bath temperature of 70°C;

[0010] S4: precipitation step, adjusting the pH value of the leaching solution to 8 with ammonia water, reacting at 60° C. for 2 hours to precipitate lithium phosphate, and obtaining the lithium phosphate product through suction filtration and drying.

[0011] Furthermore, in the pretreatment step, the particle size of the positive and negative electrode materials after crushing is controlled within the range of 0.2-2 mm.

[0012] Furthermore, in the physical separation step, the physical separation method is eddy current separation, which uses an alternating magnetic field to separate metal impurities from positive and negative electrode materials due to differences in conductivity, wherein the rotation speed of the magnetic roller of the alternating magnetic field is controlled between 3-8r / s, and the feed speed is controlled between 0.5-1.5m / s.

[0013] Furthermore, during the eddy current separation, when there are particles with a particle size less than 2 mm in the material, they need to be screened and removed first to avoid affecting the separation effect.

[0014] Furthermore, in the leaching step, the capacity of the three-necked flask is 200-300 mL, and continuous stirring is required during the leaching process. The stirring device uses a stirring paddle made of polytetrafluoroethylene.

[0015] Furthermore, in the leaching treatment step, the purity of the phosphoric acid reaches above analytical grade, and deionized water is used when preparing the phosphoric acid solution.

[0016] Furthermore, in the precipitation step, the concentration of ammonia water is 1-3 mol / L, and it needs to be slowly added dropwise during the pH adjustment process.

[0017] Furthermore, in the drying step, the drying temperature is controlled between 80-100° C. and the drying time is 4-6 hours.

[0018] Furthermore, during the entire recycling process, the waste gas generated needs to be purified. The waste gas purification equipment uses a combination of activated carbon adsorption and alkaline solution spraying to remove harmful gases.

[0019] The beneficial effects of the present invention are as follows: by controlling the acid leaching conditions, the present invention can more effectively recover lithium resources and reduce waste of resources compared to some traditional leaching methods. The present invention utilizes eddy current sorting technology, based on the significant difference in conductivity between positive and negative electrode materials and metal impurities, to achieve effective separation of metal impurities in an alternating magnetic field. By reasonably regulating the magnetic roller rotation speed and feed speed of the alternating magnetic field, metal impurities such as Al, Cu, etc. in the positive and negative electrode materials can be accurately removed, thereby significantly improving the purity of subsequent recovered products, so that the final lithium phosphate product has higher quality and is more in line with industrial application standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flow chart of a method for recycling waste lithium ion electrons.

[0021] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0024] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0025] Reference Figure 1 The present invention aims to provide an embodiment of a method for recycling waste lithium ion electrons, which specifically comprises the following steps:

[0026] S1. Preprocessing:

[0027] First, the collected waste lithium-ion batteries are placed in special discharge equipment and slowly discharged according to the set program to ensure that the battery voltage drops to a safe range. During this process, the battery voltage must be continuously monitored until it stabilizes at a low level, below 1V, to prevent dangerous situations such as short circuits during subsequent disassembly.

[0028] After discharge, the battery is disassembled using automated disassembly equipment. The equipment carefully separates components such as positive and negative electrode materials, separators, and electrolytes through precise robotic arms and cutting tools. During the separation process, gentle vibration and airflow-assisted separation technology are used for tightly adhered parts to ensure that each component is completely separated and material loss is minimized.

[0029] The separated positive and negative electrode materials are crushed by a high-precision crusher. A special screening device is installed inside the crusher to monitor the particle size of the crushed particles in real time and control it within the range of 0.2-2mm. During the crushing process, intermittent crushing and cooling cycle operation is adopted to avoid overheating of the material due to long-term continuous crushing and affecting its performance. The crushed materials are collected in a sealed stainless steel container for standby use.

[0030] S2. Physical separation:

[0031] The eddy current separation equipment is used to process the crushed positive and negative electrode materials. The alternating magnetic field generating device of the equipment adopts a combination of high-performance permanent magnets and electromagnetic coils to generate a stable alternating magnetic field with adjustable strength. Before the separation operation, the speed of the magnetic roller of the alternating magnetic field is precisely adjusted between 3-8r / s according to the characteristics of the material and the previous experimental data, and the feed speed is controlled between 0.5-1.5m / s.

[0032] When the material enters the eddy current separation area, due to the significant difference in conductivity between metal impurities and positive and negative electrode materials, eddy currents will quickly be generated inside the metal impurities under the action of the alternating magnetic field, thereby forming a reverse magnetic field, which causes them to be repelled and separated from the positive and negative electrode materials. If there are particles with a particle size less than 2mm in the material, they are first removed by a vibrating screening device. The screening device uses multiple layers of screens with different apertures to efficiently screen out particles that do not meet the particle size requirements to prevent them from affecting the eddy current separation effect. The separated positive and negative electrode materials and metal impurities enter their respective collection containers through different collection pipes. The collection containers are made of anti-static material to prevent material loss due to electrostatic adsorption during the collection process.

[0033] S3, leaching treatment:

[0034] Accurately weigh the positive electrode material that has been initially separated by S2 and place it in a 250mL three-necked flask. When preparing the phosphoric acid solution, use a phosphoric acid reagent with a purity of more than 98% (analytical grade or above), use a high-precision electronic balance to accurately weigh the required mass, and then use deionized water to accurately prepare it in a volumetric flask to ensure that the phosphoric acid concentration is 3.41mol / L. Slowly add the prepared phosphoric acid solution to the three-necked flask at a solid-liquid ratio of 1:5 so that the positive electrode material is completely immersed in the solution.

[0035] A heat-collecting constant-temperature heating magnetic stirrer is used for stirring reaction. The stirring device uses a stirring paddle made of polytetrafluoroethylene, which has good chemical stability and wear resistance. Leaching is carried out for 3 hours under the conditions of a stirring speed of 500r / min and a water bath temperature of 70°C. During the leaching process, the reaction temperature and stirring conditions are monitored in real time through temperature sensors and stirring speed sensors, and the data is transmitted to the intelligent control system to ensure stable reaction. If the temperature deviates, the control system will automatically adjust the heating power; if the stirring speed is abnormal, an alarm will be issued in time and stirring will be stopped, and the reaction will continue after the fault is eliminated.

[0036] S4, precipitation:

[0037] After the leaching is completed, the reaction solution in the three-necked flask is quickly transferred to the Buchner funnel through the connected silicone tube and filtered using a circulating water vacuum pump. The Buchner funnel is pre-placed with filter paper of appropriate pore size to ensure that the leaching solution can pass through the filter paper smoothly, while the residue remains on the filter paper, thereby obtaining a clear leaching solution.

[0038] The leachate was transferred to a stainless steel reaction vessel with a sealing cover and a stirring device, and the pH value was adjusted to 8 using 2 mol / L ammonia water. During the adjustment process, a high-precision burette was used to slowly add ammonia water, and a pH electrode was used to monitor the pH value changes in real time. The pH electrode was connected to an automatic control device. When the pH value was close to 8, the automatic control device would reduce the titration speed to prevent excessive fluctuations in the pH value.

[0039] The reaction vessel is placed in a heat-collecting constant temperature heating magnetic stirrer and reacted at 60°C for 2 hours to precipitate lithium phosphate. During the reaction, continuous stirring is performed to ensure uniform reaction, and the temperature controller and stirring monitor are used to ensure that the reaction temperature and stirring state are stable. After the precipitation reaction is completed, the precipitate is immediately filtered through a vacuum filtration device to obtain lithium phosphate precipitate. The filtration device is made of acid- and alkali-resistant polypropylene to prevent chemical reactions with the reaction solution.

[0040] Carefully transfer the lithium phosphate precipitate to a vacuum drying oven, set the drying temperature to 90°C (between 80-100°C) and the drying time to 5h (between 4-6h). The vacuum drying oven is equipped with a temperature distribution device and a humidity monitoring sensor to ensure that the lithium phosphate product is completely dried in a uniformly heated environment without decomposition. During the drying process, the humidity monitoring sensor monitors the humidity in the oven in real time. When the humidity drops below the set value, it indicates that the product is basically dry, and the drying operation is stopped at this time.

[0041] During the entire recycling process, waste gas containing harmful gases will be generated, such as ammonia that may be produced during leaching and precipitation. The waste gas is treated by a specially designed waste gas purification device that uses a combination of activated carbon adsorption and alkali solution spraying.

[0042] The exhaust gas first enters the adsorption layer filled with high specific surface area activated carbon. The activated carbon has undergone special activation treatment and has a rich microporous structure, which can effectively adsorb some organic impurities and odors in the exhaust gas. The adsorption layer is designed as a multi-layer structure, in which the exhaust gas flows in a circuitous manner, increasing the contact time and area with the activated carbon and improving the adsorption efficiency.

[0043] The waste gas after activated carbon adsorption enters the alkali liquid spray tower. The alkali liquid is sodium hydroxide solution with a concentration of 1mol / L. The spray tower is equipped with a high-efficiency atomizing nozzle, which can evenly spray the alkali liquid into tiny droplets to fully contact the waste gas. The acidic or alkaline harmful gases in the waste gas react chemically with the alkali liquid and are converted into harmless substances. A liquid accumulation tank is set at the bottom of the spray tower. The reaction products in the liquid accumulation tank are cleaned regularly to ensure the normal operation of the spray tower. The purified gas is discharged into the atmosphere after being tested by the gas detection device to meet the standards.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0045] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for recycling waste lithium ion electrons, characterized in that: The following steps are involved: S1: pretreatment step, disassembling the discarded lithium-ion batteries after discharge, separating the positive and negative electrode materials, separators and electrolytes, and crushing the positive and negative electrode materials; S2: physical separation step, using a physical separation method to preliminarily separate the crushed positive and negative electrode materials to remove metal impurities therein; S3: Leaching treatment step, using phosphoric acid to leach the positive electrode material after preliminary separation, controlling the phosphoric acid concentration to 3.41 mol / L, the solid-liquid ratio to 1:5, and leaching for 3 hours at a stirring speed of 500 r / min and a water bath temperature of 70°C; S4: precipitation step, adjusting the pH value of the leaching solution to 8 with ammonia water, reacting at 60° C. for 2 hours to precipitate lithium phosphate, and obtaining the lithium phosphate product through suction filtration and drying.

2. The method for recycling waste lithium ion electrons according to claim 1, characterized in that: In the pretreatment step, the particle size of the positive and negative electrode materials after crushing is controlled within the range of 0.2-2 mm.

3. The method for recycling waste lithium ion electrons according to claim 2, characterized in that: In the physical separation step, the physical separation method is eddy current separation, which uses an alternating magnetic field to separate metal impurities from positive and negative electrode materials due to differences in conductivity, wherein the rotation speed of the magnetic roller of the alternating magnetic field is controlled between 3-8r / s, and the feed speed is controlled between 0.5-1.5m / s.

4. The method for recycling waste lithium ion electrons according to claim 3, characterized in that: During the eddy current separation, if there are particles with a particle size less than 2 mm in the material, they need to be screened and removed first to avoid affecting the separation effect.

5. The method for recycling waste lithium ion electrons according to claim 4, characterized in that: In the leaching step, the capacity of the three-necked flask is 200-300 mL, and continuous stirring is required during the leaching process, and the stirring device uses a stirring paddle made of polytetrafluoroethylene.

6. The method for recycling waste lithium ion electrons according to claim 5, characterized in that: In the leaching treatment step, the purity of phosphoric acid reaches above analytical grade, and deionized water is used to prepare the phosphoric acid solution.

7. The method for recycling waste lithium ion electrons according to claim 6, characterized in that: In the precipitation step, the concentration of ammonia water is 1-3 mol / L, and it needs to be slowly added dropwise during the pH adjustment process.

8. The method for recycling waste lithium ion electrons according to claim 7, characterized in that: In the drying step, the drying temperature is controlled between 80-100° C. and the drying time is 4-6 hours.

9. The method for recycling waste lithium ion electrons according to claim 8, characterized in that: During the entire recycling process, the waste gas generated needs to be purified. The waste gas purification equipment uses a combination of activated carbon adsorption and alkaline solution spraying to remove harmful gases.

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