Multi-stage screening synergistic recovery method for anaerobic crushing of waste lithium batteries

Abstract

The invention relates to a multi-stage screening synergistic recovery method for anaerobic crushing of waste lithium batteries. The method comprises the following steps: crushing the batteries under the protection of an inert atmosphere; carrying out primary screening and iron removal on the crushed materials; carrying out multi-stage screening on the screen residue material in a closed inert atmosphere, and synchronously introducing density or electrical difference-based online collaborative sorting in at least one stage of screening process or screening gaps so as to separate light components or conductive components; collecting the product of each component; processing and recycling the process tail gas to maintain the inert atmosphere; and based on the material state information detected in real time, the multiple technological parameters are dynamically adjusted in a linkage mode. The four-flow cooperation of the material flow, the gas flow, the energy flow and the information flow is realized, and the comprehensive effects of remarkably improving the product purity and the metal recovery rate, reducing the energy consumption and the gas consumption and enhancing the process adaptability and the operation stability are achieved on the premise of guaranteeing the intrinsic safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery recycling, in particular to a multi-stage screening and recycling method for oxygen-free crushing of waste lithium batteries. BACKGROUND

[0002] With the rapid development of new energy vehicle industry, a large number of power lithium batteries enter the scrap stage, and their efficient, safe and environmentally friendly recycling has become an urgent demand of the industry. Physical recycling method is considered as an important recycling technology path due to its low energy consumption, less pollution and direct recovery of electrode materials.

[0003] At present, the mainstream physical recycling process usually includes oxygen-free crushing, screening, sorting and other steps. However, the existing technical solutions still have some systematic defects when they are applied to industrialization, which restricts the recycling efficiency, safety and economy.

[0004] Firstly, safety protection and process efficiency are difficult to coordinate. Although the existing technology generally uses inert atmosphere protection for crushing to prevent electrolyte explosion, the subsequent screening, conveying and other open or semi-open links still expose the active materials to air, which may cause oxidation, heating and even fire. If a harsh ultra-low oxygen environment control is used to achieve safety throughout the process, it will significantly increase the consumption of inert gas and operating costs. At the same time, for batteries with different state of charge (SOC), the risk of thermal runaway during the crushing process is very different, and the existing process lacks the ability to dynamically perceive and adaptively control this risk.

[0005] Secondly, there is a bottleneck in sorting accuracy and recovery rate. The current method mainly relies on single particle size screening or simply connects different sorting devices in series. Due to the complexity of the crushed materials, the black powder (electrode material) and the separator plastic, copper and aluminum scrap are seriously adhered due to static electricity and grease, which cannot be effectively separated by screening alone. This leads to low purity of the final product or low recovery rate of high-value metals. The existing process cannot deeply coordinate the screening (by size) and other sorting principles (such as density and electrical properties) in the same process space and time, and the single dimension of sorting limits the breakthrough of the overall sorting effect.

[0006] Thirdly, the process flow is rigid and lacks intelligent adaptability. Waste lithium batteries come from a wide range of sources, and their types, chemical systems and failure degrees differ greatly, resulting in large fluctuations in the characteristics of the crushed materials (such as particle size distribution, humidity and composition). When the equipment with fixed process parameters faces fluctuating incoming materials, problems such as screen clogging, decreased sorting efficiency and unstable product quality may occur. The existing technology lacks the ability to link and close-loop control the key parameters (crushing strength, screening size, sorting strength and atmosphere concentration) of the whole process based on the real-time state of the materials (such as purity and type), and the system lacks flexibility.

[0007] The application provides a multi-stage screening and recycling method for oxygen-free crushing of waste lithium batteries. SUMMARY

[0008] To solve the above technical problems, the application provides a multi-stage screening and recycling method for oxygen-free crushing of waste lithium batteries.

[0009] The application provides a multi-stage screening and recycling method for oxygen-free crushing of waste lithium batteries, which adopts the following technical scheme: A multi-stage screening and recycling method for oxygen-free crushing of waste lithium batteries, comprising the following steps: S1, oxygen-free crushing: crushing the waste lithium batteries under the protection of an inert atmosphere to obtain crushed materials; S2, first-stage screening and iron removal: performing first-stage screening on the crushed materials to separate out coarse-grained metal components, and performing iron removal treatment on the coarse-grained metal components; S3, multi-stage screening and collaborative sorting: performing at least two stages of screening on the remaining materials after the first-stage screening in a closed inert atmosphere environment to obtain subdivided materials of different particle size ranges; wherein, in at least one stage of screening or the gap between the stages of screening, a physical sorting means based on material density or electrical difference is introduced synchronously to perform online collaborative sorting on the target materials of this stage of screening, and separate out the light components or conductive components therefrom; S4, product collection: collecting each component product obtained by the steps S2 and S3; S5, tail gas treatment and atmosphere circulation: collecting and treating the dust-containing inert tail gas generated in the process, and recycling part of the purified gas to the process requiring inert atmosphere protection to maintain the inert atmosphere.

[0010] Preferably, the step S1 specifically comprises: detecting the state of charge (SOC) value of the waste lithium battery first, and then matching and adopting corresponding crushing parameters according to the SOC value to perform crushing under the protection of an inert atmosphere; The oxygen content of the inert atmosphere is controlled to be between 0.5% and 1%; and the matching of the crushing parameters according to the SOC value specifically comprises: when the SOC is less than or equal to 50%, a single-stage crushing is performed at a speed of 500-800 rpm; and when the SOC is greater than 50%, pre-crushing is performed at a speed of 300-400 rpm, and then fine crushing is performed at a speed of 600-800 rpm until the particle size of the crushed materials is less than or equal to 5 mm.

[0011] Preferably, in the step S2, the first-stage screening adopts a sieve with a mesh size of 20-30 to separate out coarse-grained metal components with a particle size greater than 0.85 mm; and the iron removal treatment is realized by an electromagnetic iron removal device.

[0012] Preferably, in step S3, the physical sorting method based on the density difference of the material is air flow sorting, specifically: an air flow sorting device is arranged below the discharge end or screen surface of the screening equipment, and the low-density diaphragm fragments and high-density electrode material particles in the current particle size material are separated by using a directional air flow of 3-8 m / s.

[0013] Preferably, in step S3, the physical sorting method based on the electrical difference of the material is high-voltage electrostatic sorting, specifically: a high-voltage electrostatic sorting device is arranged on the conveying path of the material after screening, the corona discharge voltage of the device is 20-50 kV, and the metal particles and electrode material particles with different electrical conductivity are separated by using electrostatic field force.

[0014] Preferably, step S3 specifically includes the following sub-steps: S31, secondary screening: using a 60-80 mesh screen to screen the remaining material of step S2, and separating the medium particle size material with a particle size of 0.18-0.85 mm; S32, secondary collaborative air sorting: in the screening process of step S31, the medium particle size material is simultaneously subjected to air flow sorting with an air speed of 4-6 m / s, and the diaphragm fragments are separated and removed therefrom; S33, tertiary fine screening: using a 150-200 mesh screen to screen the material treated in step S32, and obtaining fine particle electrode material powder with a particle size of less than 0.08 mm; S34, tertiary collaborative electrostatic sorting: high-voltage electrostatic sorting is performed on the fine particle electrode material powder obtained in step S33, and a small amount of metal conductive particles mixed therein are separated.

[0015] Preferably, in step S5, the dust-containing inert tail gas is treated by a combined process including cyclone dust removal, adsorption and high-efficiency filtration, so that the particulate matter concentration in the purified tail gas is ≤10 mg / m 3 , and volatile organic compounds and hydrogen fluoride gas are removed; The purified gas is refluxed to the closed environment of step S1 and / or step S3 at a reflux ratio of 60%-80%, and a distributed oxygen content monitoring point is arranged in the closed environment. When the oxygen content exceeds 1%, the amount of fresh inert gas supplemented and the reflux ratio are automatically adjusted to make the oxygen content return to the interval of 0.5%-1% within 30 seconds.

[0016] Preferably, it further includes a low-temperature waste heat recovery step: collecting the low-temperature waste heat of 80-150°C generated in the crushing and screening process for heating the air flow used in the air flow sorting or drying the fine particle electrode material powder.

[0017] Preferably, it further comprises a dynamic adaptive coordinated regulation step: real-time detection of the material state information of the key node, and linkage adjustment of at least two process parameters in crushing, screening, sorting and atmosphere circulation based on the information; wherein the real-time detection of the material state information comprises: real-time acquisition of the purity, particle size distribution and battery type of the material through near-infrared spectroscopy and machine vision recognition technology; the linkage adjustment specifically comprises: according to the identified battery type, automatically calling the pre-stored optimized process parameter package, and synchronously adjusting the crushing speed, screen aperture, sorting intensity and gas reflux ratio.

[0018] Preferably, in step S4, the fine particle electrode material powder is classified and collected according to particle size, and at least into three grades of <5 μm, 5-20 μm and 20-50 μm.

[0019] In summary, the present application includes at least one of the following beneficial technical effects: 1. The intrinsic safety is improved in coordination with the operation efficiency and economy. By combining the adaptive crushing strategy driven by SOC detection with the precise control of the micro-oxygen (0.5%-1%) interval, and equipped with a three-level explosion-proof system with millisecond response, the risk of combustion and explosion is eliminated from the source. Compared with the traditional ultra-low oxygen scheme, the consumption of inert gas (such as nitrogen) can be greatly reduced under the same safety level, solving the industry problem of balancing safety protection and high operating cost.

[0020] 2. The bottleneck of physical separation precision and recovery rate is broken. Through the online collaborative separation paradigm, wind separation (density difference) and electrostatic separation (electrical difference) are introduced simultaneously in the screening process, realizing separation as soon as production. This effectively solves the problem of secondary mixing of materials in traditional series processes, removes the diaphragm that causes clogging (extends the screen clogging period by more than 8 times), and efficiently separates fine metal impurities, ultimately significantly improving the purity of electrode material powder (black powder) and the recovery rate of copper and aluminum metals, realizing a qualitative change in separation effect.

[0021] 3. The recovery process is given excellent intelligent adaptability and operation stability. Based on real-time detection technologies such as machine vision and near-infrared spectroscopy, a dynamic adaptive control system is constructed. The system can automatically identify battery types and match the optimal process parameter package, realize global linkage adjustment of crushing, screening, sorting and atmosphere management, and ensure the stability of product quality when facing complex incoming materials. At the same time, through predictive maintenance of equipment state and low-temperature waste heat recovery, the system reliability and energy efficiency are greatly improved, the comprehensive power consumption is greatly reduced, and the leap from fixed process to intelligent coordination is realized. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a process system block diagram of a multi-stage screening collaborative recovery method for oxygen-free crushing of waste lithium batteries in an embodiment of the present application; Figure 2 is a method flow chart of a multi-stage screening and collaborative recycling method for waste lithium battery oxygen-free crushing in the embodiments of the present application; Figure 3 is a method flow chart of multi-stage screening and online collaborative sorting in the embodiments of the present application.

[0023] Mark explanation: 100, oxygen-free self-adaptive crushing unit; 200, first-stage screening and iron removal unit; 300, multi-stage screening and online collaborative sorting unit; 400, tail gas purification and atmosphere circulation unit; 500, dynamic collaborative control system. DETAILED DESCRIPTION

[0024] The following will be described in detail in combination with the accompanying Figures 1-3 The present application is further described in detail.

[0025] The embodiments of the present application disclose a multi-stage screening and collaborative recycling method for waste lithium battery oxygen-free crushing. Referring to Figure 1 The overall process system of the present application mainly includes: an oxygen-free self-adaptive crushing unit 100, a first-stage screening and iron removal unit 200, a multi-stage screening and online collaborative sorting unit 300, a tail gas purification and atmosphere circulation unit 400, and a dynamic collaborative control system 500. Each unit is connected through airtight conveying equipment (such as a screw conveyor, a closed belt conveyor) to form a continuous closed production line. The system design realizes the four-flow collaboration of material flow, gas flow, energy flow and information flow. Through the airtight connection of physical space and the intelligent control in logic, the originally fragmented safety protection, multi-stage sorting, environmental protection treatment and self-adaptive adjustment are organically integrated into a whole. Referring to Figure 2 A multi-stage screening and collaborative recycling method for waste lithium battery oxygen-free crushing, comprising the following steps: S1, oxygen-free crushing: crushing waste lithium batteries under inert atmosphere protection to obtain crushed materials; S2, first-stage screening and iron removal: first-stage screening the crushed materials to separate out coarse-grained metal components, and performing iron removal treatment on the coarse-grained metal components; S3, multi-stage screening and collaborative sorting: performing at least two stages of screening on the remaining materials after the first-stage screening in a closed inert atmosphere environment to obtain subdivided materials of different particle size intervals; wherein, in at least one stage of screening or the interval between the stages of screening, a physical sorting means based on the density or electrical difference of the materials is introduced synchronously to perform online collaborative sorting on the target materials of the stage of screening, and separate out the light components or conductive components therefrom; S4, product collection: collecting each component product obtained by the sorting of steps S2 and S3; S5, tail gas treatment and atmosphere circulation: collecting and treating the dust-containing inert tail gas generated in the process, and recycling part of the purified gas to the process requiring inert atmosphere protection to maintain the inert atmosphere; S6, dynamic adaptive coordinated control: real-time detection of material state information of key nodes, and linkage adjustment of at least two process parameters in crushing, screening, sorting and atmosphere circulation based on the information; wherein the real-time detection of material state information includes: real-time acquisition of purity, particle size distribution and battery type of the material through near-infrared spectroscopy and machine vision recognition technology; the linkage adjustment is specifically: according to the identified battery type, automatically calling the pre-stored optimized process parameter package, and synchronously adjusting the crushing speed, screen aperture, sorting strength and gas reflux ratio. Through the above steps, an integrated fully-closed process system of oxygen-free crushing, closed screening, online collaborative sorting and intelligent control is constructed, which deeply integrates multi-dimensional sorting (particle size, density, electrical property) in process and highly cooperates in time and space, and introduces a dynamic adaptive control system based on real-time sensing, thereby systematically and simultaneously solving the three core defects in the prior art that safety protection and efficiency and cost are difficult to balance, sorting precision is limited due to material adhesion, and process flow is rigid and cannot adapt to incoming material fluctuations. Finally, under the premise of ensuring intrinsic safety, the purity of main product and the recovery rate of valuable metals are significantly improved, the comprehensive energy consumption and inert gas consumption are reduced, and the production line is endowed with excellent intelligent adaptability and operation stability.

[0026] The above step S1 is specifically: This step is completed in the oxygen-free adaptive crushing unit 100. After being discharged, the waste lithium battery module or package is first sent to the SOC (state of charge) rapid detection station. This station can use electrochemical impedance spectroscopy (EIS) or open circuit voltage (OCV) calibration method to estimate the residual charge of the battery within 3-5 seconds. The detection data is uploaded to the dynamic collaborative control system 500 in real time.

[0027] Subsequently, the battery is sent to a sealed crushing cavity (such as a double-shaft shearing crusher). The cavity is connected to the tail gas purification and atmosphere circulation unit 400 through a pipeline, high-purity nitrogen gas (purity should be ≥99.99%) is introduced, and the oxygen content is stabilized at 0.5%-1% micro-oxygen-rich range in real time through multiple-point distributed oxygen content sensors (such as electrochemical oxygen sensors) in the unit. The selection of this range is based on a large number of safety experiments: when the oxygen content is higher than 1.5%, the high-temperature hot spot of crushing is easy to ignite the residual electrolyte; when it is lower than 0.3%, the nitrogen consumption cost increases exponentially, and the marginal effect of safety gain decreases significantly.

[0028] The control system 500 matches the preset crushing strategy according to the received SOC value. When SOC≤50%, the battery is determined to be a low-risk battery, and the crusher is controlled to perform single-stage strong crushing at a higher rotating speed of 500-800 rpm to directly obtain materials with a particle size of ≤5 mm, and the efficiency is optimal. When SOC>50%, the battery is determined to be a high-risk battery, and the control system first instructs the crusher to perform pre-crushing at a lower rotating speed of 300-400 rpm, only to break the battery shell and module structure, so that the battery cells are scattered, and the process produces heat gently; then, the materials enter the second-stage fine crusher (or the second stage of the same crusher), and the rotating speed is increased to 600-800 rpm to completely crush the battery cells to the target particle size. The two-stage crushing strategy of first slow and then fast effectively disperses the energy release of the high-SOC battery and avoids thermal runaway.

[0029] In addition, the crushing unit 100 integrates a three-stage explosion-proof linkage mechanism: 1. A laser flame detector is arranged on the inner wall of the cavity, and the response time is <0.1 second; 2. A nitrogen pulse fire extinguishing nozzle is arranged around the crushing shaft; 3. A mechanical automatic pressure relief valve is installed at the top of the cavity. When the detector or temperature sensor (threshold value 80°C) triggers an alarm, the system simultaneously starts fire extinguishing and pressure relief within 0.5 seconds to achieve intrinsic safety.

[0030] This step solves the sharp contradiction between safety and efficiency in the background art through SOC detection, adaptive crushing strategy, micro-oxygen-rich interval control, and three-stage explosion-proof double safety design. On the one hand, the battery risk level is differentiated for processing, and the processing efficiency is maximized under the premise of safety; on the other hand, the oxygen content is accurately controlled in the optimal interval of 0.5%-1%, and a millisecond-level response explosion suppression system is provided to eliminate the risk of explosion at the source. Compared with the traditional ultra-low oxygen scheme, the consumption of inert gas is greatly reduced, and the best balance between safety and economy is achieved.

[0031] The above step S2 is specifically: This step is completed in the first-stage screening and iron removal unit 200. The crushed materials are sent to the first-stage vibration screen (for example, a flip-flow screen) through a closed screw conveyor. The vibration screen is provided with a screen mesh of 20-30 meshes (pore size 0.85-0.6 mm), and the purpose is to quickly separate the coarse particles of copper foil, aluminum foil, and a small amount of shell fragments (particle size >0.85 mm). The coarse-grained metal components on the screen fall into a closed chute, and an electromagnetic iron removal device with a strong magnetic force (magnetic field strength ≥8000Gs) is arranged below the chute to efficiently adsorb and separate the steel shell fragments and other ferromagnetic impurities, and obtain pure copper-aluminum mixed metal particles. The undersize material (fine material with a particle size of ≤0.85 mm) enters the next unit through a closed pipeline.

[0032] This step quickly completes the preliminary enrichment and impurity removal of coarse-grained metal in a closed environment, with two significant advantages: first, by pre-screening, about 20-30% of large-sized metal components are quickly separated, greatly reducing the load of the subsequent fine separation unit and improving the overall processing capacity of the system; second, by efficient electromagnetic iron removal, ferromagnetic impurities are removed in the first step, avoiding the wear of equipment caused by iron scraps entering the subsequent links, and improving the purity of the final copper and aluminum metal products, laying a foundation for the recovery of high-value metals.

[0033] The above step S3 is specifically: This step is completed in the multi-stage screening and online collaborative separation unit 300, which is the core innovation of the present application. The unit as a whole is a closed cabin, also connected and maintained with an inert atmosphere with an oxygen content of ≤1%. Screening and separation are completed simultaneously or online in this closed space, achieving the synergy of safety and separation accuracy.

[0034] In a preferred embodiment, the step specifically includes the following sub-steps, as shown in Figure 3 . S31, secondary screening: the undersize from S2 falls into the second-stage vibrating screen (such as a high-frequency rotary vibrating screen), with a mesh size of 60-80 mesh (pore size 0.28-0.18 mm). The purpose of this stage is to separate medium-sized materials (particle size 0.18-0.85 mm), which mainly include electrode material sheets that have been stripped from the current collector but not fully powdered, smaller copper and aluminum foil sheets, and a large amount of diaphragm fragments.

[0035] S32, secondary collaborative air separation (density difference separation): to achieve simultaneous separation, an array of air jet nozzles is integrated below the screen mesh of the second-stage vibrating screen or in the discharge chute. When the material vibrates forward or falls on the screen mesh, a directional uniform air flow of 4-6 m / s is blown from below to above or horizontally. Due to the low density (<0.9 g / cm 3 ) of the diaphragm fragments and the high density (>2.0 g / cm 3 ) of the electrode material and metal particles, the air flow blows the lightweight diaphragm fragments up and separates them in real time, and collects them into the diaphragm bin through a negative pressure suction pipeline. This design integrates the screening action and the air separation force field in physical space and synchronizes them in time, greatly improving the diaphragm removal efficiency, ensuring that the diaphragm content in the material entering the subsequent process is negligible, greatly reducing the risk of blockage of the subsequent equipment and improving the subsequent separation accuracy.

[0036] S33, tertiary fine screening: the material treated in S32 enters a third fine screening machine (e.g. air flow screen or ultrasonic vibrating screen), with a mesh size of 150-200 mesh (pore size 0.10-0.074 mm). The goal of this stage is to obtain the main product, fine particle electrode material powder (black powder, particle size <0.08 mm).

[0037] S34, tertiary synergistic electrostatic separation (electrical property separation): at the discharge outlet of the tertiary screening, a sealed high-voltage electrostatic separator is connected. The fine powder is uniformly transported under negative pressure through a high-voltage electrostatic field (corona discharge voltage 30-40 kV, field strength 5-15 kV / cm). The trace amounts of copper and aluminum metal particles with excellent electrical conductivity (conductivity >10 4 S / m) quickly lose their charge and are adsorbed by the grounded roller and carried into the conductor product tank; while the electrode material powder that is a non-conductor or poor conductor (conductivity <10 -2 S / m) is thrown into the non-conductor product tank due to the charge it carries. This process can remove extremely fine metal scraps with a particle size of <0.05 mm, with a removal rate of trace metal particles ≥98%, and the purity of the final electrode material powder ≥99%.

[0038] This step deeply synergizes and integrates screening (by size), winnowing (by density) and electrostatic separation (by electrical property) in time and space. This online synergistic separation mode can real-time strip the separator in the most serious medium particle size link (S32) where the material is most prone to adhesion, fundamentally solving the problem of screen clogging (in the comparative experiment, the average clogging period is extended from 8 hours to 72 hours); and efficiently removing fine metal impurities in the final powder link (S34). The synergistic effect of multi-dimensional separation forces makes the black powder purity increase from 96.2% in the traditional process to more than 99.5%, and the copper and aluminum metal recovery rates also increase by 7.3% and 7.8% respectively, achieving a qualitative leap in separation effect.

[0039] Compared to the inherent defects of the existing technology of serial separation, first, during the transportation and transfer of the material from screening to separation, different density components (such as black powder and separator) may mix again due to gravity and electrostatic action, leading to the failure of pre-treatment before separation; second, the light separator fragments that have been dissociated during the screening process cannot be removed immediately and will enter the subsequent fine screening link with the material, which is the main cause of screen clogging; third, the independent separation equipment requires additional sealing, transportation and power units, increasing the system complexity, energy consumption and difficulty of maintaining inert gas. Unlike the traditional approach of first screening and then centralized separation, the present application proposes a new paradigm of online synergistic screening and separation, and the specific principles are compared as follows: Traditional serial mode: the material completes particle size separation in the screening machine and is discharged as a mixed pile, which is then sent to an independent separation machine by a conveying device. This process has a window of material state stagnation and secondary mixing.

[0040] The synergistic mode of the present application: in the internal dynamic process of the screening device (such as the second-stage vibrating screen), the sorting force field (such as the gas flow) is introduced in real time. When the material is thrown and loosened on the screen, the density difference components (membrane and electrode particles) are separated and removed by the gas flow at the best time. This realizes the generation and separation, and eliminates the secondary mixing. At the same time, the membranes removed in real time avoid entering the next-stage fine screen, and the plugging problem is solved from the source. In summary, the online synergistic separation paradigm of generating and separating is the core mechanism of improving the separation precision and the reliability of the device.

[0041] The step S4 is specifically: The products at each stage are collected by the respective closed collection devices: the pure copper-aluminum mixed metal particles obtained in S2; the membrane fragments collected in S32; the trace metal conductor particles separated in S34; and the high-purity fine-particle electrode material powder obtained in S33. Further, after the three-stage screening, an air flow classifier can be connected to finely divide the black powder into three grades according to the particle size: <5 μm (ultra-fine powder), 5-20 μm (fine powder), and 20-50 μm (coarse powder), which are packaged separately to meet the regeneration requirements of the positive electrode material with different performance requirements in the downstream.

[0042] This step realizes the efficient, closed collection and high-value directional output of all components. Not only the valuable metals such as copper and aluminum are recovered, but also the membrane fragments that are difficult to handle in the traditional process are separately collected for subsequent resourceization or environmental disposal. Especially, the particle size grading of the main product black powder can produce positive electrode material regeneration raw materials that meet different performance requirements (such as high rate and high capacity), which significantly improves the added value and market adaptability of the product, and embodies the advanced concept of fine and resourceful recycling.

[0043] The step S5 is specifically: This step is completed in the tail gas purification and atmosphere circulation unit 400. The dust-containing inert tail gas generated by each closed unit of the entire system is uniformly sucked into the purification system. The tail gas first passes through multiple-stage cyclone separators to remove most of the coarse particles with a particle size >10 μm; then enters the activated carbon adsorption tower to adsorb and remove VOCs (such as DMC, EC) and trace amounts of HF and other harmful gases generated by electrolyte volatilization; and finally passes through a high-efficiency filter cartridge dust remover (with a filtration precision of 0.3 μm) to make the particulate matter concentration in the discharged tail gas ≤10 mg / m 3 .

[0044] The cleaned inert gas (mainly nitrogen) is not discharged in its entirety, but is delivered back to the crushing cavity of S1 and the closed screening cabin of S3 at a reflux ratio of 60%-80% through a circulating fan to maintain its inert atmosphere. At the same time, the system dynamically adjusts the reflux ratio and the amount of fresh nitrogen according to the real-time data of the distributed oxygen content monitoring points in the cabin. For example, when the oxygen content monitoring value of a certain point exceeds 1%, the control system immediately increases the fresh nitrogen supply by 20%-30% and temporarily reduces the reflux ratio to 50%-60%. Usually, it can make the oxygen content return to the safe interval (0.5%-1%) within 30 seconds. This dynamic circulation strategy minimizes the consumption of fresh inert gas while ensuring safety.

[0045] This step builds an efficient internal circulation environmental protection and safety guarantee system. On the one hand, through the combined process of cyclone, adsorption and filtration, the environmental protection problem of dust and harmful gas emission is completely solved, realizing clean production. On the other hand, the unique dynamic atmosphere circulation technology, through intelligent adjustment of reflux ratio and air supply, stabilizes the safe oxygen concentration while minimizing the consumption of inert gas, which is one of the core technologies to realize the economic feasibility of the invention, and the nitrogen consumption per ton is greatly reduced.

[0046] The above step S6 is specifically: This function is executed by the dynamic cooperative control system 500, realizing the global optimization of information flow, material flow, gas flow and energy flow.

[0047] Information perception: Deploy a sensor network at key nodes. At the feed end, use a combination of machine vision and a miniature X-ray fluorescence (XRF) probe to identify battery types (ternary, lithium iron phosphate, lithium cobaltate, etc.) within 3 seconds. After secondary screening and tertiary screening, install an online near-infrared (NIR) spectrum analyzer to monitor the characteristic peak intensity of elements such as copper, aluminum, cobalt and nickel in the material in real time, and calculate the product purity and composition.

[0048] Data-driven and linked regulation: The control system 500 has a built-in process parameter linkage database, which pre-stores optimized process parameter packages for different battery types. For example, for ternary lithium batteries with high viscosity, the parameter package is set as: crushing speed 600-800 rpm, tertiary screen mesh size 180-200 mesh, and static voltage 35-40 kV; for brittle lithium iron phosphate batteries, the parameter package is set as: crushing speed 500-700 rpm, tertiary screen mesh size 150-180 mesh, and static voltage 30-35 kV. When the vision system identifies a change in battery type or the NIR detects that the black powder purity is continuously below the set threshold (such as 99%) for 10 seconds, the system automatically calls and switches the parameter package within 30 seconds, and sends instructions to the crushing machine, vibration screen frequency converter, air separation fan, and electrostatic separator high-voltage power supply to complete the coordinated adjustment of global parameters.

[0049] Device health management and energy efficiency optimization: The system collects real-time operation data such as vibration, temperature, and current of each host device. By analyzing the vibration spectrum, it can predict and screen for screen clogging or bearing wear. When the vibration frequency of a certain screening machine deviates from the set value by ±10% or the energy consumption abnormally increases by 20%, the system will automatically fine-tune the process parameters (such as adjusting the amplitude or reducing the load) to maintain production, and also send a precise predictive maintenance warning to the maintenance personnel, reducing unplanned downtime.

[0050] Energy flow coordination: The system integrates a low-temperature waste heat recovery circuit. It collects the cooling waste heat generated by the crusher and vibration motor at 80-150℃, and heats the air flow entering the air separation device to 40-60℃ through a plate heat exchanger, which not only improves the air separation efficiency (reduces air humidity and enhances material dispersion), but also saves energy consumption for air flow heating. The overall system can achieve significant energy consumption reduction, and this energy flow coordination design is one of the important factors for achieving a 13.9% reduction in overall energy consumption (see example data).

[0051] This step gives the entire process system a smart brain, directly solving the rigidity of the process flow and the lack of intelligent adaptability in the prior art. Through real-time sensing-decision-execution closed-loop control, the system can automatically adapt to fluctuations in incoming materials (battery type, SOC), ensuring that the process is always in an optimal state and ensuring stable product quality. Predictive maintenance reduces unexpected downtime, and waste heat recovery further reduces energy consumption, achieving a leap from fixed processes to intelligent coordination and from high energy consumption to energy optimization.

[0052] To verify the technical effects of the present application, the following comparative experiments were conducted.

[0053] Comparative Example 1: Using the traditional process: nitrogen protection crushing (oxygen content <2%) → open-air multi-stage vibration screening (no online collaborative separation) → separate air separation and electrostatic separation of screening products. The processing object of the separate air separation and electrostatic separation machine in Comparative Example 1 is the corresponding particle size material obtained after the same multi-stage screening to ensure consistency in the comparison.

[0054] Inventive Example: The method and system of the present application are used, with the following specific parameters: SOC adaptive crushing (threshold 50%), two-stage screening (80 mesh) integrated with online air separation (air speed 5 m / s), three-stage screening (200 mesh) followed by online electrostatic separation (voltage 35 kV), dynamic atmosphere circulation (reflux ratio 70%), and automatic parameter package matching function based on XRF identification (processing object is ternary lithium battery).

[0055]

[0056] The experimental results show that the application is superior to the traditional process in product purity, metal recovery rate, safety, running stability and energy consumption, and achieves the purpose of the application.

[0057] Those skilled in the art can understand that, without departing from the core principle of the application, several substitutions and improvements can be made. 1、The airflow sorting device can also adopt a vertical air duct type or a Zigzag airflow separator in addition to the array nozzle type.

[0058] 2、The electrostatic sorting can adopt a roller type, a plate type or a free-falling type electrode structure.

[0059] 3、The battery type identification can also adopt laser-induced breakdown spectroscopy (LIBS) or mid-infrared spectroscopy (MIR) in addition to the combination of vision and XRF.

[0060] 4、In the tail gas purification process, activated carbon adsorption can be replaced or connected in parallel with zeolite rotary adsorption concentration and catalytic oxidation devices to treat larger air volume or higher concentration of VOCs.

[0061] These substitutions all belong to the routine technical selection under the core concept of the application disclosed, that is, multi-stage screening and online collaborative sorting, dynamic self-adaptive regulation, and should fall within the protection scope of the application.

[0062] The above examples are only used to illustrate the technical solutions of the application, and not to limit the protection scope of the application. Obviously, the described examples are only some of the embodiments of the application, not all the embodiments. Based on these examples, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of the application to be protected. Although the application is described in detail with reference to the above examples, those skilled in the art can still combine, add or delete or make other adjustments to the features in the embodiments of the application according to the circumstances without creative labor, so as to obtain different other technical solutions which do not deviate from the concept of the application in essence, and these technical solutions also belong to the scope of the application to be protected.

Claims

1. A multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries, characterized in that, Includes the following steps: S1. Oxygen-free crushing: Under the protection of an inert atmosphere, waste lithium batteries are crushed to obtain crushed materials; S2. Primary screening and iron removal: The crushed material is subjected to primary screening to separate coarse metal components, and the coarse metal components are subjected to iron removal treatment. S3. Multi-stage screening and co-sorting: The remaining material after primary screening is screened at least twice in a closed inert atmosphere to obtain subdivided materials with different particle size ranges; wherein, during at least one screening process or between screenings, physical sorting methods based on material density or electrical differences are introduced simultaneously to perform online co-sorting of the target material for that screening stage, separating the light or conductive components. S4. Product collection: Collect the components obtained from steps S2 and S3; S5. Exhaust gas treatment and atmosphere circulation: Collect and treat the dust-containing inert exhaust gas generated during the process, and return part of the purified gas to the process that requires inert atmosphere protection in order to maintain the inert atmosphere.

2. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, Step S1 specifically includes: first, detecting the state of charge (SOC) value of the waste lithium battery, then matching and using the corresponding crushing parameters based on the SOC value, and crushing the battery under an inert atmosphere. The oxygen content of the inert atmosphere is controlled between 0.5% and 1%. The crushing parameters are matched according to the SOC value as follows: when SOC ≤ 50%, single-stage crushing is performed at a speed of 500-800 rpm; when SOC > 50%, pre-crushing is performed at a speed of 300-400 rpm, followed by fine crushing at a speed of 600-800 rpm, until the particle size of the crushed material is ≤ 5 mm.

3. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, In step S2, the first-stage screening uses a 20-30 mesh screen to separate coarse metal components with a particle size greater than 0.85 mm; the iron removal process is achieved by an electromagnetic iron removal device.

4. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, In step S3, the physical separation method based on the material density difference is airflow separation, specifically: an airflow separation device is set at the discharge end of the screening equipment or below the screen surface, and a directional airflow of 3-8m / s is used to separate low-density diaphragm fragments and high-density electrode material particles in the material of the current particle size.

5. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, In step S3, the physical sorting method based on the difference in electrical properties of materials is high-voltage electrostatic sorting. Specifically, a high-voltage electrostatic sorting device is set up on the conveying path of the screened material. The corona discharge voltage of the device is 20-50kV, and the electrostatic field force is used to separate metal particles with different conductivity from electrode material particles.

6. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, Step S3 specifically includes the following sub-steps: S31, Secondary screening: The remaining material from step S2 is screened using a 60-80 mesh sieve to separate medium-sized material with a particle size of 0.18-0.85 mm. S32, Secondary Cooperative Air Separation: During the screening process in step S31, the medium-sized material is simultaneously subjected to air separation with a wind speed of 4-6 m / s to separate and remove the membrane fragments. S33, three-stage fine screening: the material after step S32 is screened using a 150-200 mesh sieve to obtain fine-particle electrode material powder with a particle size of less than 0.08 mm. S34, Three-stage coordinated electrostatic separation: High-voltage electrostatic separation is performed on the fine-particle electrode material powder obtained in step S33 to separate out the trace amounts of conductive metal particles mixed in it.

7. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, In step S5, the treatment of dust-laden inert exhaust gas specifically employs a combined process including cyclone dust removal, adsorption, and high-efficiency filtration, ensuring that the particulate matter concentration in the purified exhaust gas is ≤10mg / m³. 3 It also removes volatile organic compounds and hydrogen fluoride gas; The purified gas is returned to the closed environment of step S1 and / or step S3 at a reflux ratio of 60%-80%; and distributed oxygen content monitoring points are set up in the closed environment. When the oxygen content is detected to exceed 1%, the replenishment amount and reflux ratio of fresh inert gas are automatically adjusted so that the oxygen content returns to the range of 0.5%-1% within 30 seconds.

8. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 6, characterized in that, It also includes a low-temperature waste heat recovery step: collecting low-temperature waste heat of 80-150℃ generated in the crushing and screening process, which is used to heat the airflow used in the air classifier or to dry the fine-particle electrode material powder.

9. The multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 1, characterized in that, It also includes a dynamic adaptive collaborative control step: real-time detection of material status information at key nodes, and linkage adjustment of at least two process parameters in crushing, screening, sorting and atmosphere circulation based on the information; The real-time detection of material status information includes: acquiring the purity, particle size distribution, and battery type of the material in real time through near-infrared spectroscopy and machine vision recognition technology; The linkage adjustment specifically involves: automatically calling the pre-stored optimized process parameter package according to the identified battery type, and synchronously adjusting the crushing speed, screen aperture, sorting intensity, and gas reflux ratio.

10. A multi-stage screening and synergistic recycling method for oxygen-free crushing of waste lithium batteries according to claim 6, characterized in that, In step S4, the fine-particle electrode material powder is collected and classified according to its particle size, and is divided into at least three grades: <5μm, 5-20μm, and 20-50μm.

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