A silicon-carbon negative electrode material production device and method based on hot-knife separation and waste heat recycling

Abstract

The application discloses a kind of based on hot knife separation and waste heat reuse silicon-carbon negative electrode material production equipment and method, equipment includes central control system and is connected in turn by conveying system and takes box device, frame removal mechanism, hot knife separation module and detection and separation device, detection and separation device are connected by pneumatic slide rail and the feed inlet of jaw crusher, the discharge outlet of jaw crusher is connected by pneumatic conveying pipeline and the feed inlet of silver extraction machine, the discharge outlet of silver extraction machine is connected by pneumatic conveying pipeline and the feed bin of ball mill, the discharge outlet of ball mill is connected by screw feeder and spray drying tower, spray drying tower is connected by conveying pipeline and joule heating device, and the exhaust port of spray drying tower is sequentially connected with activated carbon adsorption tank and induced draft fan by pipeline, hot knife separation module and detection and separation device are connected with central control system. The present application can promote the high-value recovery and resource utilization of waste photovoltaic modules.

Description

Technical Field

[0001] This invention relates to the recycling of waste photovoltaic modules, specifically a silicon-carbon anode material production equipment and method based on hot knife separation and waste heat recovery. Background Technology

[0002] Global photovoltaic (PV) installed capacity has exceeded 1500GW, while the lifespan of PV modules is 25-30 years, which will soon trigger a large-scale decommissioning wave. It is predicted that by 2030, the annual output of waste PV modules worldwide will exceed 8 million tons, of which 90% are crystalline silicon modules. If landfill disposal is adopted, toxic substances such as lead-containing solder ribbons and EVA films can easily seep into the soil and groundwater, causing serious pollution. At the same time, the glass and aluminum frame resources in PV modules will be wasted.

[0003] However, existing photovoltaic module recycling technologies have the following drawbacks: 1) Mechanical and physical separation methods generally have an efficiency of less than 70%, and the purity of the extracted silicon powder is less than 90%; 2) Although heat treatment can improve the separation efficiency, the high temperature of 600℃ during heat treatment causes damage to the silicon wafer lattice, and the energy consumption of heat treatment is too high, usually 800-1200 kWh / ton; 3) Chemical dissolution methods, through hydrofluoric acid treatment, can obtain silicon with a purity greater than 99%, but generate fluoride-containing wastewater (3-5m³). 3 The processing cost has surged by 30% (per ton). Furthermore, existing technologies struggle to completely separate silicon wafers from glass, resulting in recycled silicon powder mixed with glass fragments and metal impurities. When directly used in silicon-carbon anodes, the capacity retention rate is less than 20% after 500 cycles, far below commercial requirements. Therefore, the recycling and processing of retired photovoltaic modules faces two major contradictions: first, the environmental risks of massive amounts of discarded modules versus inefficient resource utilization; and second, the high cost of silicon-carbon anode raw materials versus the low quality of recycled silicon powder. Thus, there is an urgent need to develop innovative technologies that combine efficient separation, low energy consumption, and high-value utilization to overcome the core barriers to the coordinated development of the photovoltaic recycling and energy storage industries.

[0004] Furthermore, the lithium-ion battery industry has seen a surge in demand for silicon-carbon anode materials, but these materials rely on high-purity metallurgical silicon or nano-silicon powder. Purification costs often account for more than 20% of the total cost, and production is energy-intensive, consuming over 12,000 kWh of electricity per ton. Therefore, efficiently recycling silicon wafers from waste photovoltaic modules and using them to prepare silicon-carbon anode materials is of great significance for the recycling of waste photovoltaic modules and the development of the lithium-ion battery industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a silicon-carbon anode material production equipment and method based on hot knife separation and waste heat recovery, thereby promoting the high-value recycling and resource utilization of silicon wafers in waste photovoltaic modules.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery includes a central control system and a box-removing device, a frame removal mechanism, a hot knife separation module, and a detection and separation device connected in sequence through a conveying system. The detection and separation device is connected to the feed inlet of a jaw crusher via a pneumatic slide rail. The discharge outlet of the jaw crusher is connected to the feed inlet of a silver lifting machine via a pneumatic conveying pipe. The discharge outlet of the silver lifting machine is connected to the feed hopper of a ball mill via a pneumatic conveying pipe. The discharge outlet of the ball mill is connected to a spray drying tower via a screw feeder. The spray drying tower is connected to a Joule heating device via a conveying pipe. The exhaust outlet of the spray drying tower is connected to an activated carbon adsorption box and an induced draft fan in sequence via a pipe.

[0008] The hot knife separation module includes a constant temperature heating chamber, an array of hot knives, and a pressure sensor. Both the array of hot knives and the pressure sensor are connected to the central control system.

[0009] The detection and separation device includes a vacuum chuck array, an electromagnetic sorting module, a CCD visual positioning system, and an X-ray fluorescence spectrometer for real-time monitoring of cadmium and tellurium content. The X-ray fluorescence spectrometer, CCD visual positioning system, electromagnetic sorting module, and vacuum chuck array are all connected to the central control system.

[0010] Furthermore, it also includes pulse dust collectors, TO furnaces, and waste heat recovery systems;

[0011] The exhaust port of the pulse dust collector is connected to the exhaust port of the hot knife separation module through a pipe, the exhaust port of the pulse dust collector is connected to the exhaust port of the TO furnace through a pipe, and the exhaust port of the TO furnace is connected to the exhaust port of the hot knife separation module.

[0012] The waste heat recovery system includes a spiral heat exchange tube assembly and a hot air circulation pipe. The spiral heat exchange tube assembly is wound around the outer wall of the TO furnace, and the hot air circulation pipe is connected to the constant temperature heating chamber.

[0013] Furthermore, the interlayer of the TO furnace is filled with a composite phase change heat storage body, which is composed of Al-Si alloy and NaNO3-KNO3 mixed salt.

[0014] Furthermore, the array-type hot knife assembly consists of multiple sets of independently temperature-controlled wedge-shaped blades, the surface of which is coated with a nano-ceramic coating.

[0015] Furthermore, the pneumatic slide rail has a slide rail tilt angle of 15°, and its surface is covered with a polyurethane wear-resistant layer.

[0016] Furthermore, the jaw crusher is hydraulically driven, and the working surfaces of its moving jaw plate and fixed jaw plate have a corrugated tooth structure, with the tooth height of the corrugated tooth structure being 3-5mm.

[0017] The angle between the jaw plate and the fixed jaw plate in the breaking chamber is 18-22°.

[0018] Furthermore, the pneumatic conveying pipeline is made of stainless steel, and the inner wall of the pneumatic conveying pipeline is coated with polytetrafluoroethylene; and a particle size analyzer is installed in the middle section of the pneumatic conveying pipeline used to connect the jaw crusher and the silver lifting machine, and the particle size analyzer is connected to the central control system.

[0019] Furthermore, the ball mill is a planetary ball mill and is equipped with an in-situ atmosphere control system, which includes an argon gas replacement unit, a temperature monitoring module, and a cooling jacket. The argon gas replacement unit is a porous gas distributor located on the top of the grinding jar of the ball mill; the temperature monitoring module is an infrared thermal imager array surrounding the outer wall of the grinding jar; and the cooling jacket is a double-layer stainless steel sleeve covering the grinding jar.

[0020] Furthermore, a weighing module is installed at the discharge port of the ball mill, and the weighing module is connected to the central control system.

[0021] A method for producing silicon-carbon anode materials based on hot knife separation and waste heat recovery includes the following steps:

[0022] Step 1: The junction box of the waste photovoltaic module is first removed by the box removal device, and then the aluminum frame is peeled off by the frame removal mechanism. Then it is sent to the hot knife separation module by the conveying system. The array of hot knives cuts into the EVA adhesive layer at 320°C and 0.6MPa pressure to separate the glass and silicon wafer.

[0023] The exhaust gas generated by the hot knife separation module is transported to the pulse dust collector, which removes silicon-containing dust from the exhaust gas. The exhaust gas after being cleaned by the pulse dust collector enters the TO furnace, which generates medium-temperature gas at 300-400°C. The medium-temperature gas enters the hot knife separation module, which heats the inside of the constant temperature heating chamber to 300°C.

[0024] Step 2: The silicon wafer and glass are conveyed to the detection and separation device via a conveying system. The CCD vision positioning system identifies the position of the silicon wafer through multispectral imaging, and the cadmium and tellurium content is monitored in real time by an X-ray fluorescence spectrometer. When the content reaches the set threshold, the vacuum suction cup array is triggered to isolate the contaminant material. Otherwise, the vacuum suction cup array picks up the silicon wafer and conveys it to the pneumatic slide rail. At the same time, the electromagnetic sorting module sorts metal impurities and lead-containing solder strip fragments with a gradient magnetic field of 1.0T to 1.5T.

[0025] Step 3: The pneumatic slide rail transports the sorted silicon wafers to the jaw crusher, crushes them to D = 10 ± 3 mm, and then transports them to the silver extraction machine through the pneumatic conveying pipeline to extract the silver electrodes. Then the silicon wafers enter the ball mill. Under the protection of argon gas, the carbon source is added into the ball mill according to the mass ratio of silicon powder to carbon source (0.2~1):1. The ball mill performs ball milling on the mixture of silicon powder and carbon source to obtain silicon-carbon composite powder with D < 10 μm.

[0026] Step 4: The low-temperature gas of 100-150℃ discharged from the hot knife separation module is transported to the spray drying tower for preheating. At the same time, the silicon-carbon composite powder enters the spray drying tower and is granulated into particles of 20-50μm. The particles enter the Joule heating device filled with argon. The Joule heating system adopts a stepped heating strategy, first preheating at 250℃, then heating to 500℃~2000℃ for sintering, so that a uniform carbon coating layer of 20-40nm is formed on the silicon surface. Then it is slowly cooled at 120℃, and the finished silicon-carbon anode material with lead residue of less than 5ppm is output.

[0027] The exhaust gas generated by the spray drying tower is drawn into the activated carbon adsorption box for treatment of volatile organic compounds under the negative pressure generated by the induced draft fan.

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] First, temperature-controlled hot knife separation technology achieves non-destructive peeling of photovoltaic laminated materials, with a separation efficiency >95% and a damage depth of <5μm to the silicon wafer surface, reducing damage by 90% compared to traditional mechanical cutting processes. Second, the detection and separation device separates the silicon wafers and removes metal impurities and lead-containing solder fragments, resulting in silicon powder purity >99.95% and metal impurities <50ppm after crushing, improving sorting accuracy by 30 times compared to traditional processes. Third, the waste heat from TO furnace pyrolysis exhaust gas is used for material drying, reducing overall energy consumption to 1.2 tons of standard coal / ton, achieving an energy saving rate of 57%. Fourth, under an argon atmosphere, in-situ carbon coating of silicon yields high-purity silicon-carbon anode materials with a tap density >1.2 g / cm³. 3 First, it improves the energy density of the battery, with the first discharge efficiency of the assembled battery exceeding 91% and the cycle life reaching 500 times. Second, the exhaust gas generated by the spray drying tower is purified by adsorption, and the emission indicators are better than the EU Best Feasible Technology (EU BAT) standard. Third, the central control system realizes the coordinated control of equipment through a digital twin model, which increases the utilization rate of raw materials of waste photovoltaic modules to 99.2%, is compatible with waste silicon materials and metallurgical silicon slag, reduces production costs by 58%, and has an annual processing capacity of 15,000 tons per line, which can reduce hazardous waste landfill by 48,000 cubic meters per year, providing an efficient and clean circular economy paradigm for the new energy industry. Attached Figure Description

[0030] Figure 1: A schematic diagram of the overall structure of the present invention;

[0031] Figure 2 : A schematic diagram of the structure of the hot knife separation module coupling detection and separation device of the present invention;

[0032] Figure 3 : A schematic diagram of the Joule heating device of the present invention;

[0033] Figure 4 : Process flow diagram of the present invention.

[0034] In the diagram: 1. Box removal device; 2. Frame removal mechanism; 3. Conveying system; 4. Hot knife separation module; 5. Detection and separation device; 6. Jaw crusher; 7. Silver extraction machine; 8. Ball mill; 9. Pulse dust collector; 10. TO furnace; 11. Activated carbon adsorption box; 12. Exhaust fan; 13. Spray drying tower; 14. Joule heating device; 15. Waste heat recovery system; 16. Central control system; 17. Constant temperature heating chamber; 18. Array-type hot knife group; 19. Pressure sensor; 20. Vacuum suction cup array; 21. Electromagnetic sorting module; 22. Moving jaw plate; 23. Fixed jaw plate; 24. Feeding system; 25. Integrated electrode sintering system; 26. Cooling and discharging system; 27. Inert atmosphere control device. Detailed Implementation

[0035] The specific content of the present invention will be further explained in detail below with reference to the embodiments.

[0036] like Figures 1-3 As shown, a silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery includes a box-removing device 1, a frame removal mechanism 2, a conveying system 3, a hot knife separation module 4, a detection and separation device 5, a jaw crusher 6, a silver extraction machine 7, a ball mill 8, a pulse dust collector 9, a TO furnace 10, an activated carbon adsorption box 11, an induced draft fan 12, a spray drying tower 13, a Joule heating device 14, a waste heat recovery system 15, and a central control system 16.

[0037] The box-removing device 1, the frame removal mechanism 2, and the hot knife separation module 4 are connected in sequence through the conveying system 3. The waste photovoltaic module is laser-positioned and the junction box is cut off by the box-removing device 1 with a cutting accuracy of ±0.1mm. It is then conveyed to the frame removal mechanism 2 through the conveying system 3. The hydraulically driven frame removal mechanism 2 peels off the aluminum frame at an 18° tilt angle with a hydraulic pressure of 18MPa. The conveying system 3 then conveys the waste photovoltaic module with the junction box and aluminum frame removed to the hot knife separation module 4.

[0038] The hot knife separation module 4 includes a constant temperature heating chamber 17, an array of hot knife groups 18, and a pressure sensor 19. The temperature control range of the constant temperature heating chamber 17 is 250℃~450℃. The array of hot knife groups 18 consists of multiple sets of independently temperature-controlled wedge-shaped blades, and the blade surface is coated with a nano-ceramic coating. The pressure sensor 19 is linked with the blade drive mechanism to monitor the blade insertion pressure in real time and adjust the pressing speed. At 320℃, the array of hot knife groups 18 cuts into the EVA adhesive layer of the waste photovoltaic module with a pressure of 0.6MPa, separating the glass from the silicon wafer.

[0039] The discharge port of the hot knife separation module 4 is connected to the detection and separation device 5 via the conveying system 3. The detection and separation device 5 includes a vacuum suction cup array 20, an electromagnetic sorting module 21, a CCD vision positioning system, and an X-ray fluorescence spectrometer. The vacuum suction cup array 20 consists of 32 independently controlled vacuum suction cups arranged in a 4×8 matrix. Each suction cup has a flexible silicone sealing ring at its bottom. The CCD vision positioning system uses spectral imaging to acquire the three-dimensional coordinate data of the silicon wafer, thereby identifying the wafer's position. The silicon wafer is precisely adsorbed into the positioning groove of the silicon wafer conveyor belt in the conveying system 3 at a vacuum level of -80kPa to -100kPa. The electromagnetic sorting module 21 uses a Helmholtz coil structure to generate a gradient magnetic field of 1.0T to 1.5T, and is equipped with a vibrating screening mechanism with an amplitude of 0.5-1.2mm and a frequency of 15-25Hz. Combined with a pulsed airflow of 1.5-2.5m / s, it sorts metal impurities with a particle size of 50-200μm. The X-ray fluorescence spectrometer is used to monitor cadmium and tellurium content in real time.

[0040] The silicon wafer conveyor belt outlet of the detection and separation device 5 is connected to the feed inlet of the jaw crusher 6 via a pneumatic slide rail. The slide rail has an inclination angle of 15° and its surface is covered with a polyurethane wear-resistant layer. A photoelectric sensor for starting and stopping the jaw crusher 6 is installed at the end of the slide rail. The detection frequency of the photoelectric sensor is 100Hz.

[0041] The jaw crusher 6 is hydraulically driven. The working surfaces of its movable jaw plate 22 and fixed jaw plate 23 have a corrugated tooth structure with a tooth height of 3-5mm and a crushing chamber angle of 18-22°. The movable jaw plate 22 and fixed jaw plate 23 are crushed into 10±3mm particles with an 8mm gap. The silicon wafers are conveyed to the jaw crusher 6 through the conveying system 3 and crushed to a diameter D=10mm by the jaw crusher 6.

[0042] The discharge port of the jaw crusher 6 is connected to the feed port of the silver lifting machine 7 through a pneumatic conveying pipe. The inner wall of the pneumatic conveying pipe is coated with polytetrafluoroethylene. A particle size analyzer is installed in the middle section of the pipe. When a particle size > 15mm is detected, the return valve is triggered to send the material back to the jaw crusher 6.

[0043] The silicon wafers crushed by the jaw crusher 6 are conveyed to the silver extraction machine 7 through a pneumatic conveying pipeline to extract the silver electrodes from the silicon wafers. The silver extraction machine 7 adopts high-voltage electrostatic-eddy current composite separation with a voltage of 28kV and a magnetic roller speed of 1800rpm, and the removal rate of lead impurities is greater than 98.5%.

[0044] The discharge port of the silver extraction machine 7 is connected to the feed hopper of the ball mill 8 through a Φ200mm stainless steel pneumatic conveying pipe. The pipe is equipped with a Venturi injector with a working pressure of 0.25MPa and a three-way feed valve with a switching response time of <0.5s to realize the directional conveying of silicon powder and the diversion of impurities. There are two ball mills 8, and the two ball mills 8 are connected in sequence through a stainless steel pneumatic conveying pipe. The silicon wafers for extracting silver electrodes are conveyed to the ball mill 8 by the conveying system 3. The silicon wafers are mixed with carbon source at a mass ratio of 1:0.3. Under argon protection, the mixture is ball-milled for 4 hours to obtain silicon-carbon composite powder with D <10μm.

[0045] Preferably, the ball mill 8 is a planetary ball mill, equipped with a zirconium oxide grinding jar and silicon carbide grinding balls, with a grinding ball diameter gradient of 5mm, 8mm and 10mm in three grades, a silicon powder to carbon powder mass ratio of (0.2~1):1, a ball-to-material ratio of (10~15):1, and a rotation speed of 300-500rpm.

[0046] The ball mill 8 is equipped with an in-situ atmosphere control system, which includes an argon gas replacement unit, a temperature monitoring module, and a cooling jacket. The argon gas replacement unit is a porous gas distributor at the top of the grinding jar of the ball mill 8. High-purity argon gas is continuously introduced into the grinding jar at a flow rate of 5-15 L / min through the porous gas distributor at the top of the grinding jar, so that the oxygen content inside the grinding jar is maintained below 50 ppm. The temperature monitoring module consists of an infrared thermal imager array arranged around the outer wall of the grinding jar. It monitors the surface temperature distribution of the jar in real time at a sampling frequency of 20 frames per second and feeds the temperature data back to the central control system 16. The cooling jacket adopts a double-layer stainless steel sleeve structure to cover the grinding jar. An ethylene glycol aqueous solution with a temperature range of -10℃ to 5℃ circulates inside the jacket. The working temperature of the grinding jar is stabilized within the range of 25±5℃ by adjusting the solution flow rate.

[0047] The discharge port of the ball mill 8 is connected to the spray drying tower 13 via a screw feeder. A weighing module is installed at the outlet of the feeder and is connected to the central control system 16. The height of the spray drying tower 13 is 8-12 meters. The inlet temperature of the spray drying tower 13 is 180-220℃, the outlet temperature is 80-100℃, and the rotation speed of the atomizing disc is 15000-25000 rpm. The silicon-carbon composite powder is dried inside the spray drying tower 13 to obtain spherical particles with a diameter of 10-50μm.

[0048] The spray drying tower 13 is connected to the Joule heating device 14 via a conveying pipeline. The Joule heating device 14 includes a feeding system 24, an electrode sintering system 25, a cooling and discharging system 26, and an inert atmosphere control device 27. The feeding system 24 has automatic feeding, automatic stirring, and weighing feedback functions. The integrated electrode sintering system 25, under argon protection, sintersulates the dried silicon-carbon composite powder at a sintering temperature of 500℃-2000℃, forming a uniform carbon coating layer 20-40nm thick on the silicon surface. The inert atmosphere control device 27 dynamically adjusts the atmosphere based on detection results. The cooling and discharging system 26 is used to cool the sintered silicon-carbon anode and send it to the collection box.

[0049] The Joule heating system 14 is equipped with a specific surface area tester at the feed inlet to detect the specific surface area of ​​the material in real time. The specific surface area tester is connected to the central control system 16. The central control system 16 synchronously adjusts the power (±3%) of the array-type hot knife group 18 and the sintering temperature (±5℃) inside the electrode sintering system 25 to obtain a silicon-carbon anode with an initial charge-discharge efficiency of >90% and a capacity retention rate of >89% after 500 cycles at 1C.

[0050] The spray drying tower 13 is coupled to the hot air circulation pipe of the waste heat recovery system 15. The waste heat recovery system 15 is connected to the hot knife separation module 4. The exhaust port of the hot knife separation module 4 is connected to the pulse dust collector 9 through a pipe. When the vacuum suction cup array 20 adsorbs silicon wafers, the negative pressure of the pulse dust collector 9 is triggered to collect lead dust. The exhaust port of the pulse dust collector 9 is connected to the TO furnace 10 through a pipe. The flue gas after dust removal is transported to the TO furnace 10, purified by combustion and heated. The exhaust port of the TO furnace 10 is connected to the air inlet of the hot knife separation module 4. The heated gas is transported to the hot knife separation module 4.

[0051] The waste heat recovery system 15 includes a spiral heat exchange tube assembly and a hot air circulation pipe. The spiral heat exchange tube assembly is wound around the outer wall of the TO furnace 10, with a heat exchange efficiency greater than 80%. The 400°C waste gas emitted from the TO furnace 10 is heat-exchanged through the spiral heat exchange tube assembly. The jacket of the TO furnace 10 is filled with a composite phase change heat storage body, which is filled with a mixture of Al-Si alloy and NaNO3-KNO3 salt. The phase change temperature of the Al-Si alloy is 580°C, and the phase change temperature of the NaNO3-KNO3 mixture is 220°C. The hot air circulation pipe transports the 300-400°C medium-temperature gas generated by the TO furnace 10 to the constant temperature heating chamber 17 of the hot knife separation module 4, and then transports the 100-150°C low-temperature gas discharged from the hot knife separation module 4 to the spray drying tower 13.

[0052] The exhaust port of the spray drying tower 13 is connected in sequence to the activated carbon adsorption box 11 and the induced draft fan 12 through a pipe. Under the negative pressure generated by the induced draft fan 12, the exhaust gas discharged from the spray drying tower 13 is sent into the activated carbon adsorption box 11. The activated carbon adsorption box 11 treats volatile organic compounds and deeply removes lead. The removal rate of benzene series compounds by the activated carbon adsorption box 11 is greater than 99%.

[0053] The central control system 16, in conjunction with the pulse dust collector 9 and the activated carbon adsorption box 11, ensures that dust and VOCs emissions meet standards, ultimately achieving a single-line daily processing capacity of 25 tons, with a silicon-carbon negative electrode tap density ≥1.2 g / cm³. 3 The overall energy consumption was reduced to 0.9 tons of standard coal per ton;

[0054] The central control system 16 integrates a crushing particle size closed-loop control module, a carbon doping optimization module, and a sintering quality prediction module. Specifically: the crushing particle size closed-loop control module dynamically adjusts the hydraulic pressure of the jaw crusher 6 based on data from the particle size analyzer, with a control accuracy of ±0.1MPa; the carbon doping optimization module automatically adjusts the carbon source addition ratio based on feedback data from the specific surface area analyzer using a PID algorithm, with an adjustment resolution of ±0.5wt%; and the sintering quality prediction module uses a machine learning model to analyze the mapping relationship between the sintering temperature curve and the electrochemical performance of the material.

[0055] This embodiment constructs a feedforward-feedback dual-channel control based on the existing PID algorithm. The feedforward channel predicts the optimal amount of carbon source to be added based on the data from the specific surface area meter and through an artificial neural network (ANN). The feedback channel adopts an incremental PID algorithm to fine-tune the carbon source addition rate in 0.1wt% steps and introduces process constraints. When the Fe content of silicon powder is detected to be >200ppm, the carbon source over-compensation mode (+0.3wt%) is triggered to suppress the catalytic side reaction of metal impurities.

[0056] Preferably, in the ball mill 8, the recovered silicon powder and biomass carbon are dry-mixed, and the biomass carbon is coconut shell carbon with a specific surface area of ​​1200 m². 2 / g.

[0057] Preferably, the conveying system 3 is equipped with a stainless steel guide channel with an inclination angle of 12°, and the surface of the channel is coated with a 200μm thick polytetrafluoroethylene coating to prevent lead dust from adhering.

[0058] Preferably, the temperature range inside the constant temperature heating cavity 17 is 250±5℃.

[0059] Preferably, the downward pressing speed of the array-type hot knife group 18 is adjusted by the central control system 16 and controlled at 0.1-0.3 m / min to suppress the generation of lead vapor.

[0060] Preferably, the electromagnetic sorting module 21 sorts lead-containing solder strip fragments with a 1.2T gradient magnetic field.

[0061] Preferably, the conveying system 3 is further provided with a 40kHz ultrasonic cleaning tank between the frame removal mechanism 2 and the hot knife separation module 4. The material enters the ultrasonic cleaning tank through a concave conveyor belt and removes the PET protective layer with 25% isopropanol.

[0062] This embodiment improves the lead removal rate from waste photovoltaic modules by 40% compared to traditional processes, meeting the lead content standard (<10ppm) of GB / T30882-2014 "Silicon Materials for Electronic Industry". Moreover, waste heat recycling reduces the energy consumption of the separation section by 52%.

[0063] Preferably, when co-processing electronic waste, the rollers of the conveying system 3 can be equipped with a double-spiral mixing chamber with an adjustable speed of 15-25 rpm. Waste circuit board powder (D50 = 15μm) and silicon powder are uniformly mixed at a mass ratio of 1:1.5. The mixture enters the detection and separation device 5 through a Φ200mm pneumatic conveying pipe with a ceramic liner. The electromagnetic sorting module 21 is loaded with a 1.0T gradient magnetic field, and the magnetic roller speed is dynamically adjusted to 800-1200 rpm and the sorting gap to 5-8mm by the programmable logic controller (PLC) to achieve online sorting of copper and silver. The sorted silicon-based mixture enters the feeding system 2 of the Joule heating device 14. 4. First, pyrolysis is performed at 450℃ with an argon flow rate of 10L / min for 30min to remove organic matter. Then, alloying is carried out at 850℃, and a 3% hydrogen-argon mixture is introduced to carry out a silicon-metal eutectic reaction. Then, granulation is performed at 1250℃ with an atomization pressure of 8MPa to prepare 50-80μm spherical particles. The integrated electrode sintering system 25 maintains an oxygen content of <50ppm through an inert atmosphere control device 27. The cooling and discharge system 26 uses nitrogen rapid cooling at a cooling rate of 50℃ / min to suppress grain coarsening. Finally, a silicon-based alloy anode is obtained with a specific capacity of not less than 1800mAh / g and a capacity retention rate of >85% after 500 cycles.

[0064] Preferably, this embodiment can be configured as a digital twin system, wherein: the central control system 16 integrates a real-time sensor network and algorithm model, and installs high-precision wear sensors (accuracy ±0.005mm) on the array-type hot knife group 18 of the hot knife separation module 4 to dynamically monitor the tool life and link with the deep learning model to predict the hot knife replacement cycle error <3%; multi-channel temperature probes with an error of ±2℃ are deployed in the TO furnace 10, and a digital mirror of the sintering temperature field is constructed in combination with three-dimensional simulation to optimize heating parameters in real time; the visualization interface dynamically displays the stress distribution of the jaw crusher 6, the atomization status of the spray drying tower 13, and the ball wear rate of the ball mill 8, and simultaneously marks the energy consumption heat map of key equipment (color temperature gradient label); the system adopts a multi-objective optimization algorithm to automatically generate process schemes (such as hot knife pressure 0.25MPa, sintering heating rate 8℃ / min), and controls parameters in real time through the industrial Internet of Things to increase the production capacity by 40% to 2.1 tons / hour and reduce the product defect rate to 0.18% (compliant with IEC). (ISO 23247-3 standard); An intelligent control module is deployed between the pulse dust collector 9 and the activated carbon adsorption box 11 to dynamically adjust the operating frequency of the induced draft fan 12. The exhaust gas treatment efficiency is >99%, and the overall system computing power load is <35%, meeting the requirements of the ISO 23247-3 digital twin standard.

[0065] Preferably, the hot knife separation module 4 is equipped with a spraying mechanism, which sprays a 3% ammonium bifluoride solution with a pH of 4.5 to soften the EVA adhesive layer, thereby reducing the cutting pressure of the array-type hot knife group 18 to 0.15 MPa and the temperature to 220°C.

[0066] like Figure 4 As shown, a method for producing silicon-carbon anode materials based on hot knife separation and waste heat recovery includes the following steps:

[0067] Step 1: The waste photovoltaic module first has its junction box cut off by laser positioning of the box removal device 1, and then the aluminum frame is peeled off by the hydraulically driven frame removal mechanism 2 at an 18° angle. It is then sent to the hot knife separation module 4 via the conveying system 3. The array-type hot knife group 18 cuts into the EVA adhesive layer at 320°C and 0.6MPa pressure to separate the glass and silicon wafer. The exhaust gas generated by the hot knife separation module 4 is sent to the pulse dust collector 9 to remove silicon dust. The exhaust gas after being removed by the pulse dust collector 9 enters the TO furnace 10, and after pyrolysis, it generates medium-temperature gas at 300-400°C. The medium-temperature gas enters the hot knife separation module 4 and heats the inside of the constant temperature heating chamber 17 to 300°C.

[0068] Step 2: The silicon wafer and glass are sent to the detection and separation device 5 via the conveying system 3. The detection and separation device 5 identifies the position of the silicon wafer through multispectral imaging and monitors the cadmium and tellurium content in real time through X-ray fluorescence spectrometer. When the content reaches the set threshold, the vacuum suction cup array 20 is triggered to isolate the contaminant material. The heavy metal residue in the silicon powder is <3ppm. Otherwise, the vacuum suction cup array 20 picks up the silicon wafer and moves it to the pneumatic slide rail. The electromagnetic sorting module 21 sorts the metal impurities and lead-containing solder strip fragments with a 1.5T gradient magnetic field.

[0069] Step 3: The silicon wafer is conveyed to the jaw crusher 6 and crushed to D = 10 ± 3 mm. Then it is sent to the silver extraction machine 7 to extract the silver electrode. After the silver electrode is extracted by the silver extraction machine 7, the silicon wafer enters the ball mill 8. Under the protection of argon gas, the loss-in-weight feeder of the ball mill 8 feeds carbon nanotubes into the ball mill 8 at a mass ratio of silicon powder to carbon source of 1:0.3. The ball mill 8 ball mills the mixture of silicon powder and carbon nanotubes for 4 hours to obtain silicon-carbon composite powder with D < 10 μm.

[0070] Step 4: The composite powder enters the spray drying tower 13 and is granulated into particles of 20-50μm. The particles then enter the Joule heating device 14. The purity of the argon gas in the Joule heating system 14 is greater than 99.99%. It adopts a stepped heating strategy, first preheating at 500℃ and then sintering at 1200℃ to form a uniform carbon coating layer of 20-40nm on the silicon surface. Then it is slowly cooled and cooled and discharged through the nitrogen-sealed channel of the discharge system 26 (oxygen content less than 50ppm) to output finished silicon-carbon anode material with lead residue less than 5ppm.

[0071] The waste gas generated by the spray drying tower 13 is drawn into the activated carbon adsorption box 11 for treatment of volatile organic compounds under the negative pressure generated by the induced draft fan 12.

[0072] Application Example 1

[0073] Retired photovoltaic modules enter the pre-processing section via an automated conveyor line. The junction box removal device 1 locates the junction box using a vision system and precisely cuts it off using a hydraulic shear head with a pressure of 0.3 MPa. Then, the frame removal mechanism 2, with its four servo grippers and a 2000 N·m torque rotating head, peels off the aluminum frame within 30 seconds (the aluminum frame recovery rate is 99.2%). The pre-processed modules then enter the hot knife separation module 4 via the conveyor system 3. An array of hot knife blades 18 inserts wedge-shaped blades at a speed of 0.1 mm / s and a constant temperature of 380°C between the layers. A pressure sensor dynamically adjusts the downward pressure from 0.5 to 1.0 MPa, achieving micron-level separation of the glass and silicon wafers. The separated silicon wafers are picked up by a vacuum suction cup array 20 and fed into a jaw crusher 6. A corrugated toothed moving jaw plate 22 applies pressure at 25 MPa. The silicon wafers are crushed into 15-20mm particles using force and a 22° cavity angle, with a crushing efficiency of 3 tons / hour. The crushed material enters the silver extraction machine 7 through a pneumatic pipe with a polytetrafluoroethylene lining. The silver electrode is recovered through an electrostatic-magnetic separation composite process (recovery efficiency > 98%). The silver-extracted silicon powder enters the ball mill 8, using three-stage silicon carbide grinding balls of 5mm, 8mm, and 10mm, with a ball-to-material ratio of 10:1. Straw carbon source with ash content less than 5% is added. The grinding is carried out at 480rpm for 12 hours. Ethylene glycol at -5℃ is introduced into the cooling jacket of the ball mill 8, and the temperature is controlled at ≤20℃. Silicon-carbon composite powder with a particle size of 2.5μm is produced. After granulation in the spray drying tower 13, the powder enters the Joule heating device 14 and is sintered at 1000℃ to obtain silicon-carbon anode material.

[0074] The activated carbon adsorption box 11 purifies the exhaust gas discharged from the spray drying tower 13, reducing the total non-methane hydrocarbons to less than 12 mg / m³. 3 In accordance with GB 30484, the waste heat recovery system 15 supplies the 400℃ waste heat generated by the TO furnace 10 to the hot knife module 4, and the waste heat supplied to the hot knife module 4 generates 100℃ waste heat for the spray drying tower 13.

[0075] In the above process, the central control system 16 dynamically adjusts the jaw plate spacing and carbon doping. XRF verification shows that the carbon content is 10±0.3wt%, and the resulting silicon-carbon anode material is used in power batteries. The initial charge-discharge efficiency is 89.5%, and the capacity retention rate after 100 cycles at 0.5C is 91%, which meets the GB / T 36276-2018 power battery standard.

[0076] Application Example 2

[0077] In the production of silicon-carbon anodes, a jaw crusher 6 crushes silicon particles through the corrugated toothed layering of the moving jaw plate 22 and the fixed jaw plate 23. The hydraulic pressure is 25±0.5MPa, and the water cooling system has a temperature ΔT < 10℃. The resulting silicon particles have a D50 of 20±2mm. These particles are then quantitatively conveyed to a ball mill 8 via a Φ150mm silicon nitride-coated pneumatic pipeline at a wind speed of 2.8m / s. Simultaneously, 8.0wt% of pretreated carbon source is added using a loss-in-weight feeder with an accuracy of ±0.05%. The pretreated carbon source is obtained by activating waste newspaper with hydrochloric acid, washing it with water, and pre-carbonizing it at 800℃. The carbon source has an ash content of no more than 2.7%. The ball mill 8 starts the argon purging program, with its top-mounted annular distributor introducing 99.999% argon at 12 L / min. The vacuum pump evacuates at -0.08 MPa, reducing the oxygen content to 35 ppm within 15 minutes. Three-stage silicon carbide grinding balls of 5 mm, 8 mm, and 10 mm are used in a 3:5:2 volume ratio, with a ball-to-material ratio of 12:1. Mechanical alloying is performed at 480 rpm. The central control system 16 dynamically regulates the -5℃ ethylene glycol flow rate in the cooling jacket using a 0.1℃ resolution infrared thermal imager (PID control 8m). 3 The grinding temperature was maintained at 55±3℃ for 8 hours to obtain composite powder with D50=1.8±0.2μm. The slurry was pumped to the mixing tank by a screw pump (1200s-1 shear rate), and 0.8wt% CMC (degree of substitution 0.7) and 0.2wt% SDBS were added. The online rheometer was used to adjust the solid content to 35.0±0.3%, viscosity to 120±15mPa·s (25℃), and Zeta potential to -35±2mV. The heat recovered by the waste heat recovery system 15 entered the spray drying tower 13 at 160℃. Through waste heat recovery, the energy consumption of the drying tower 13 was reduced by 27%. The internal temperature of the spray drying tower 13 was then raised to 200±3℃, and granulation with a 22000±200rpm atomizing disc at a pressure of 4.5MPa was carried out to form spherical particles with D50=40±3μm and a tap density of 1.85±0.05g / cm³. 3 The Joule heating device 14 performs gradient sintering, stress release at 500℃ / 1.5h (XRD half-peak width decreases by 40%) → carbothermal reduction at 1200℃ / 4h (H / Ar mixed gas, reaction SiO+3C→β-SiC+2CO↑), followed by slow cooling to obtain silicon-carbon anode material.

[0078] The obtained silicon-carbon anode material was used in a power battery. At 0.1C, the discharge capacity was 2105±12mAh / g, the coulombic efficiency was 92.3%, and the capacity retention rate was 89.5% after 500 cycles at 1C, with a volume expansion rate of 7.8%.

[0079] The overall energy consumption of this application example is 11.5 kWh / kg, which complies with GB / T 23331-2020 and represents a 37.8% reduction in energy consumption compared to traditional processes.

[0080] Application Example 3

[0081] After the junction box of the retired photovoltaic module is removed by laser cutting by the box removal device 1, the frame removal mechanism 2 peels off the aluminum frame with a pressure of 20MPa through hydraulic shearing. The conveying system 3 feeds the module into the hot knife separation module 4 at a speed of 0.8m / s. The array-type hot knife group 18 is maintained at 320±5℃ in the constant temperature heating chamber 17. The pressure sensor 19 adjusts the pressure under the blades in real time to 0.6-0.8MPa, realizing non-destructive separation of glass and silicon wafers. The separated silicon wafers are adsorbed and positioned by the vacuum suction cup array 20 of the detection and separation device 5. The electromagnetic sorting module 21 sorts metal impurities with a magnetic field strength of 1.2T (copper and silver recovery rate is greater than 98%). The silicon wafers enter the jaw crusher 6 through the conveying system 3. The moving jaw plate 22 and the fixed jaw plate 23 crush the silicon wafers into 10±3mm particles with a corrugated tooth structure with a tooth height of 5mm and an 18° crushing chamber angle. The crushed material passes through the inner wall with The polytetrafluoroethylene-coated pneumatic pipeline transports the silicon powder to the silver extraction machine 7, where it is further purified by 25kV high-voltage electrostatic separation to reduce the silver residue to less than 0.03%. The silver-extracted silicon powder enters the ball mill 8, where three-stage silicon carbide grinding balls of 5mm, 8mm, and 10mm are used at a ball-to-material ratio of 12:1. Under argon protection (i.e., the oxygen content is maintained at less than 50ppm by the inert atmosphere control device 27), the grinding is carried out for 8 hours. The tank temperature is controlled by the waste heat recovery system 15 with fluctuations of <±3℃. The ball milling product is atomized by 200℃ hot air in the spray drying tower 13 with an atomizing disc speed of 22000rpm to form silicon-carbon composite powder with a particle size of 20-50μm. Subsequently, it enters the integrated electrode sintering system 25 of the Joule heating device 14 and undergoes stepped sintering under an argon atmosphere: 500℃ preheating → 1200℃ carbon coating → nitrogen rapid cooling in the cooling and discharge system 26 to obtain silicon-carbon anode material.

[0082] The pulse dust collector 9 captures 99.9% of the dust in the exhaust gas discharged from the hot knife separation module 4, and the activated carbon adsorption box 11 purifies the tail gas discharged from the spray drying tower 13, resulting in non-methane total hydrocarbons <15mg / m³. 3 The central control system 16 dynamically optimizes the hot knife pressure through the pressure sensor 19, and interlocks and controls the gap accuracy of the jaw crusher 6 to ±0.1mm, the speed accuracy of the ball mill 8 to ±5rpm, and the Joule heating temperature to ±10℃. The waste heat recovery system 15 utilizes the 400℃ waste gas generated by the TO furnace 10 and the 120℃ tail gas generated by the hot knife separation module 4 in a cascade manner, reducing the comprehensive energy consumption to 1.3 tons of standard coal / ton.

[0083] The resulting silicon-carbon anode material was used in a power battery, achieving an initial charge-discharge efficiency of 91%, a capacity retention of 89% after 500 cycles at 1C, and a tap density of 1.25 g / cm³. 3 It conforms to the GB / T 36276-2018 standard.

Claims

1. A silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery, characterized in that, The system includes a central control system (16) and a box-removing device (1), a frame removal mechanism (2), a hot knife separation module (4), and a detection and separation device (5) connected in sequence via a conveying system (3). The detection and separation device (5) is connected to the feed inlet of a jaw crusher (6) via a pneumatic slide rail. The discharge outlet of the jaw crusher (6) is connected to the feed inlet of a silver lifting machine (7) via a pneumatic conveying pipe. The discharge outlet of the silver lifting machine (7) is connected to the feed hopper of a ball mill (8) via a pneumatic conveying pipe. The discharge outlet of the ball mill (8) is connected to a spray drying tower (13) via a screw feeder. The spray drying tower (13) is connected to a Joule heating device (14) via a conveying pipe. The exhaust outlet of the spray drying tower (13) is connected in sequence to an activated carbon adsorption box (11) and an induced draft fan (12) via a pipe. The hot knife separation module (4) includes a constant temperature heating chamber (17), an array of hot knives (18), and a pressure sensor (19). The array of hot knives (18) and the pressure sensor (19) are both connected to the central control system (16). The detection and separation device (5) includes a vacuum chuck array (20), an electromagnetic sorting module (21), a CCD visual positioning system, and an X-ray fluorescence spectrometer for real-time monitoring of cadmium and tellurium content. The X-ray fluorescence spectrometer, the CCD visual positioning system, the electromagnetic sorting module (21), and the vacuum chuck array (20) are all connected to the central control system (16).

2. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to claim 1, characterized in that, It also includes a pulse dust collector (9), a TO furnace (10), and a waste heat recovery system (15); The exhaust ports of the pulse dust collector (9) and the hot knife separation module (4) are connected by pipes. The exhaust port of the pulse dust collector (9) is connected to the inlet of the TO furnace (10) by pipes. The exhaust port of the TO furnace (10) is connected to the inlet of the hot knife separation module (4). The waste heat recovery system (15) includes a spiral heat exchange tube assembly and a hot air circulation pipe. The spiral heat exchange tube assembly is wound around the outer wall of the TO furnace (10), and the hot air circulation pipe is connected to the constant temperature heating chamber (17).

3. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to claim 2, characterized in that, The interlayer of the TO furnace (10) is filled with a composite phase change heat storage body, which is composed of Al-Si alloy and NaNO3-KNO3 mixed salt.

4. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to any one of claims 1 to 3, characterized in that, The array-type hot knife assembly (18) consists of multiple sets of wedge-shaped blades with independently controllable temperature, and the blade surface is coated with a nano-ceramic coating.

5. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to any one of claims 1 to 3, characterized in that, The pneumatic slide rail has a tilt angle of 15° and its surface is covered with a polyurethane wear-resistant layer.

6. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to any one of claims 1 to 3, characterized in that, The jaw crusher (6) is hydraulically driven, and the working surfaces of its moving jaw plate (22) and fixed jaw plate (23) have a corrugated tooth structure, and the tooth height of the corrugated tooth structure is 3-5 mm. The angle between the movable jaw plate (22) and the fixed jaw plate (23) in the crushing chamber is 18~22°.

7. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to any one of claims 1 to 3, characterized in that, The pneumatic conveying pipeline is made of stainless steel and the inner wall of the pneumatic conveying pipeline is coated with polytetrafluoroethylene; and a particle size analyzer is installed in the middle section of the pneumatic conveying pipeline used to connect the jaw crusher (6) and the silver lifting machine (7), and the particle size analyzer is connected to the central control system (16).

8. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to any one of claims 1 to 3, characterized in that, The ball mill (8) is a planetary ball mill and is equipped with an in-situ atmosphere control system. The system includes an argon gas replacement unit, a temperature monitoring module and a cooling jacket. The argon gas replacement unit is a porous gas distributor set on the top of the grinding tank of the ball mill (8). The temperature monitoring module is an infrared thermal imager array surrounding the outer wall of the grinding tank. The cooling jacket is a double-layer stainless steel sleeve covering the grinding tank.

9. The silicon-carbon anode material production equipment based on hot knife separation and waste heat recovery according to any one of claims 1 to 3, characterized in that, The ball mill (8) is equipped with a weighing module at its discharge port, and the weighing module is connected to the central control system (16).

10. A method for producing silicon-carbon anode materials based on hot knife separation and waste heat recovery using the equipment described in claim 2, characterized in that, Includes the following steps: Step 1: The waste photovoltaic module first cuts off the junction box through the box removal device (1), then peels off the aluminum frame through the frame removal mechanism (2), and then is sent into the hot knife separation module (4) by the conveying system (3). The array-type hot knife group 18 cuts into the EVA adhesive layer at 320°C with a pressure of 0.6 MPa to separate the glass and silicon wafer. The exhaust gas generated by the hot knife separation module (4) is transported to the pulse dust collector (9). The pulse dust collector (9) removes silicon dust from the exhaust gas. The exhaust gas after being removed by the pulse dust collector (9) enters the TO furnace (10). The TO furnace (10) generates medium-temperature gas at 300-400°C. The medium-temperature gas enters the hot knife separation module (4) and heats the inside of the constant temperature heating chamber (17) to 300°C. Step 2: The silicon wafer and glass are sent to the detection and separation device (5) via the conveying system (3). The CCD vision positioning system identifies the position of the silicon wafer through multispectral imaging and monitors the cadmium and tellurium content in real time through the X-ray fluorescence spectrometer. When the content reaches the set threshold, the vacuum suction cup array (20) is triggered to isolate the contaminant material. Otherwise, the vacuum suction cup array (20) picks up the silicon wafer and transports it to the pneumatic slide rail. At the same time, the electromagnetic sorting module (21) sorts metal impurities and lead-containing solder strip fragments with a gradient magnetic field of 1.0T~1.5T. Step 3: The pneumatic slide rail transports the sorted silicon wafers to the jaw crusher (6), crushes them to D=10±3mm, and then transports them to the silver extractor (7) through the pneumatic conveying pipeline to extract the silver electrode. Then the silicon wafers enter the ball mill (8). Under the protection of argon gas, the carbon source is added into the ball mill (8) according to the mass ratio of silicon powder to carbon source (0.2~1):

1. The ball mill (8) ball mills the mixture of silicon powder and carbon source to obtain silicon-carbon composite powder with D<10μm. Step 4: The low-temperature gas of 100-150℃ discharged from the hot knife separation module (4) is transported to the spray drying tower (13) for preheating. At the same time, the silicon-carbon composite powder enters the spray drying tower (13) and is granulated into particles of 20-50μm. The particles enter the Joule heating device (14) filled with argon. The Joule heating device (14) adopts a step heating strategy, first preheating at 250℃, then heating to 500℃~2000℃ for sintering, so that a uniform carbon coating layer of 20-40 nm is formed on the silicon surface. Then it is slowly cooled at 120℃, and the finished silicon-carbon anode material with lead residue of less than 5 ppm is output. The exhaust gas generated by the spray drying tower (13) is drawn into the activated carbon adsorption box (11) for treatment of volatile organic compounds under the negative pressure generated by the induced draft fan (12).

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