Silicon-carbon negative electrode material production equipment and method based on hot knife separation and waste heat recycling

Abstract

The invention discloses silicon-carbon negative electrode material production equipment and method based on heat knife separation and waste heat recycling, and the equipment comprises a central control system, and a box taking device, a frame dismounting mechanism, a heat knife separation module and a detection and separation device which are sequentially connected through a conveying system, the detection and separation device is connected with a feeding port of the jaw crusher through a pneumatic sliding rail, a discharging port of the jaw crusher is connected with a feeding port of the silver extraction machine through a pneumatic conveying pipeline, a discharging port of the silver extraction machine is connected with a feeding bin of the ball mill through a pneumatic conveying pipeline, and a discharging port of the ball mill is connected with the spray drying tower through the spiral feeder. The spray drying tower is connected with the Joule heating device through a conveying pipeline, an exhaust port of the spray drying tower is sequentially connected with an activated carbon adsorption box and an induced draft fan through pipelines, and the heat knife separation module and the detection and separation device are both connected with the central control system. According to the method, high-value recovery and resource utilization of the silicon wafers in the waste photovoltaic module can be promoted.

Description

Technical Field

[0001] The present invention relates to the recycling of waste photovoltaic modules, and specifically to a production device and method for silicon-carbon anode materials based on hot-knife separation and waste heat reuse. Background Art

[0002] The global photovoltaic installed capacity has exceeded 1500 GW, and the service life of photovoltaic modules is 25 - 30 years, which will soon trigger a large-scale retirement wave. It is predicted that the annual output of global waste photovoltaic modules will exceed 8 million tons in 2030, and 90% of them are crystalline silicon modules. If landfilled, toxic substances such as lead solder tapes and EVA films are likely to seep into the soil and groundwater, causing serious pollution. At the same time, the glass and aluminum frame resources in photovoltaic modules are wasted.

[0003] However, the existing photovoltaic module recycling technologies have the following defects respectively: 1) The separation efficiency of mechanical-physical methods is generally lower than <70%, and the purity of the extracted silicon powder is less than 90%; 2) Although the heat treatment method can improve the separation degree, during the heat treatment process, the high temperature of 600 °C causes lattice damage to the silicon wafers, and the energy consumption of heat treatment is too high, usually 800 - 1200 kWh / ton; 3) The chemical dissolution method uses hydrofluoric acid treatment. Although silicon with a purity greater than 99% can be obtained, it generates fluorine-containing wastewater (3 - 5 m 3 / ton), and the treatment cost surges by 30%. In addition, it is difficult for the existing technology to achieve the complete peeling of silicon wafers and glass, resulting in the recycled silicon powder being mixed with glass debris and metal impurities. When directly used for silicon-carbon anodes, the capacity retention rate is less than 20% after 500 cycles of the material, far lower than the commercial requirements. It can be seen that the recycling and treatment of retired photovoltaic modules face two major contradictions: one is the contradiction between the environmental protection hazards of a large number of waste modules and the low efficiency of resource utilization; the other is the contradiction between the high cost of silicon-carbon anode raw materials and the low quality of recycled silicon powder. Therefore, it is urgent to develop innovative technologies with high-efficiency separation, low energy consumption, and high-value utilization to break through the core barriers for the coordinated development of the photovoltaic recycling and energy storage industries.

[0004] In addition, the demand for silicon-carbon anode materials in the lithium-ion battery industry has increased sharply, but its raw materials rely on high-purity metallurgical silicon or nano-silicon powder. The purification cost often accounts for more than 20% of the total cost, and the production energy consumption is large, with power consumption per ton exceeding 12000 kWh. Therefore, efficiently recycling silicon wafers from waste photovoltaic modules and using them to prepare silicon-carbon anode materials is of great significance for the development of waste photovoltaic module recycling and the lithium-ion battery industry. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a production device and method for silicon-carbon anode materials based on hot-knife separation and waste heat reuse, so as to promote the high-value recycling and resource utilization of silicon wafers in waste photovoltaic modules.

[0006] To achieve the above object, the present invention is implemented by the following technical solutions:

[0007] A production device for silicon-carbon anode materials based on hot knife separation and waste heat reuse, comprising a central control system, a box-taking device, a frame removal mechanism, a hot knife separation module, and a detection and separation device connected in sequence through a conveyor system. The detection and separation device is connected to the feeding port of a jaw crusher through a pneumatic slide rail. The discharging port of the jaw crusher is connected to the feeding port of a silver extraction machine through a pneumatic conveying pipeline. The discharging port of the silver extraction machine is connected to the feeding bin of a ball mill through a pneumatic conveying pipeline. The discharging port of the ball mill is connected to a spray drying tower through a screw feeder. The spray drying tower is connected to a Joule heating device through a conveying pipeline, and the exhaust port of the spray drying tower is sequentially connected with an activated carbon adsorption box and an induced draft fan through a pipeline;

[0008] The hot knife separation module includes a constant temperature heating cavity, an array type hot knife group, and a pressure sensor. The array type hot knife group and the pressure sensor are both connected to the central control system;

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

[0010] Furthermore, it also includes a pulse dust collector, a TO furnace, and a waste heat recovery system;

[0011] The pulse dust collector is connected to the smoke exhaust port of the hot knife separation module through a pipeline. The air outlet of the pulse dust collector is connected to the air inlet of the TO furnace through a pipeline. The air outlet of the TO furnace is connected to the air inlet of the hot knife separation module;

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

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

[0014] Furthermore, the array type hot knife group is composed of multiple groups of wedge-shaped blades with independent temperature control, and a nano-ceramic coating is provided on the blade surface.

[0015] Furthermore, the inclination angle of the slide rail of the pneumatic slide rail is 15°, and a polyurethane wear-resistant layer is laid on its surface.

[0016] Further, the jaw crusher is hydraulically driven, and the working surfaces of its movable jaw plate and fixed jaw plate are in a corrugated tooth-shaped structure, and the tooth height of the corrugated tooth-shaped structure is 3 - 5 mm;

[0017] The included angle between the jaw plate and the fixed jaw plate of the crushing chamber is 18 - 22°.

[0018] Further, the pneumatic conveying pipeline is made of stainless steel, and the inner wall of the pneumatic conveying pipeline is coated with a polytetrafluoroethylene coating; and a particle size detector is installed in the middle section of the pneumatic conveying pipeline for connecting the jaw crusher and the silver extraction machine, and the particle size detector is connected to the central control system.

[0019] Further, the ball mill is a planetary ball mill and is equipped with an in-situ atmosphere control system. The system includes an argon replacement unit, a temperature monitoring module, and a cooling jacket. Among them: the argon replacement unit is a porous gas distributor arranged at the top of the grinding tank of the ball mill; the temperature monitoring module is an array of infrared thermal imagers surrounding the outer wall of the grinding tank; the cooling jacket is a double-layer stainless steel sleeve covering the grinding tank.

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

[0021] A production method of silicon-carbon anode materials based on hot knife separation and waste heat recycling includes the following steps:

[0022] Step 1: The used photovoltaic module first removes the junction box via the box-taking device, then strips the aluminum frame via the frame removal mechanism, and then is sent into the hot knife separation module by the conveying system. The array-type hot knife group cuts into the EVA glue layer at 320 °C with a pressure of 0.6 MPa to separate the glass and the silicon wafer;

[0023] The waste gas generated by the hot knife separation module is transported to enter the pulse dust collector, and the pulse dust collector is used to remove the silicon-containing dust in the waste gas. The waste gas after being dusted by the pulse dust collector enters the TO furnace. The TO furnace generates medium-temperature gas at 300 - 400 °C, and the medium-temperature gas enters the hot knife separation module to heat the inside of the constant-temperature heating cavity to 300 °C;

[0024] Step 2: The silicon wafer and the glass are sent to the detection and separation device by the conveying system. The CCD vision positioning system identifies the position of the silicon wafer through multi-spectral imaging, and real-time monitors the cadmium and tellurium contents through the X-ray fluorescence spectrometer. When it reaches the set threshold, it triggers the vacuum suction cup array to isolate the contaminated materials. Otherwise, the vacuum suction cup array picks up the silicon wafer and transports it to the pneumatic slide rail; meanwhile, the electromagnetic separation module separates metal impurities and lead-containing solder strip fragments with a gradient magnetic field of 1.0 T - 1.5 T;

[0025] Step 3: The pneumatic slide rail transports the sorted silicon wafers to a jaw crusher, where they are crushed to D = 10 ± 3 mm, and then conveyed by a pneumatic conveying pipeline to a silver extraction machine to extract silver electrodes. Then the silicon wafers enter a ball mill. Under argon protection, a carbon source is input into the ball mill according to a mass ratio of silicon powder to carbon source of (0.2 - 1):1. The ball mill mills the mixture of silicon powder and carbon source to obtain a silicon-carbon composite powder with D < 10 μm;

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

[0027] The waste gas generated by the spray drying tower is pumped to an activated carbon adsorption box for treating volatile organic compounds under the negative pressure generated by a draft fan.

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

[0029] First, through the temperature-controlled hot knife separation technology, the lossless peeling of photovoltaic laminating materials is realized, the separation efficiency > 95%, the damage depth to the silicon wafer surface < 5 μm, and the damage is reduced by 90% compared with the traditional mechanical cutting process. Second, the detection and separation device separates the silicon wafers and removes metal impurities and lead-containing solder strip fragments, making the purity of the crushed silicon powder > 99.95%, the metal impurities < 50 ppm, and the sorting accuracy is 30 times higher than that of the traditional process. Third, the waste heat of the TO furnace pyrolysis waste gas is used for material drying, which can reduce the comprehensive energy consumption to 1.2 tons of standard coal / ton, and the energy saving rate reaches 57%. Fourth, in an argon atmosphere, silicon is coated with carbon in situ to obtain a high-purity silicon-carbon negative electrode material with a tapped density > 1.2 g / cm 3 , which improves the energy density of the battery. The first discharge efficiency of the battery assembled with it > 91% and the cycle life reaches 500 times. Fifth, the waste gas generated by the spray drying tower is purified by adsorption, and the emission index is better than the EU Best Available Techniques (EU BAT) standard. Sixth, the central control system realizes the coordinated control of equipment through a digital twin model, improves the raw material utilization rate of waste photovoltaic modules to 99.2%, is compatible with waste silicon materials and metallurgical silicon slag, reduces the production cost by 58%, the single-line annual processing capacity reaches 15,000 tons, and can reduce hazardous waste landfill by 48,000 cubic meters / year, providing an efficient and clean circular economy paradigm for the new energy industry. Description of the Drawings

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

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

[0032] Figure 3 : Schematic diagram of the structure of the Joule heating device of the present invention;

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

[0034] In the figure: 1. Box-taking device; 2. Frame removal mechanism; 3. Conveyor 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. Induced draft fan; 13. Spray drying tower; 14. Joule heating device; 15. Waste heat recovery system; 16. Central control system; 17. Constant temperature heating cavity; 18. Array type hot knife group; 19. Pressure sensor; 20. Vacuum suction cup array; 21. Electromagnetic separation module; 22. Moving jaw plate; 23. Fixed jaw plate; 24. Feeding system; 25. Integrated electrode sintering system; 26. Cooling and discharging system; 27. Inert gas control device. Detailed implementation manners

[0035] The following further explains the specific content of the present invention in detail in combination with embodiments.

[0036] As Figures 1 to 3 shown, a production device for silicon-carbon anode materials based on hot knife separation and waste heat reuse includes a box-taking device 1, a frame removal mechanism 2, a conveyor 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-taking device 1, the frame removal mechanism 2 and the hot knife separation module 4 are sequentially connected through the conveyor system 3. The waste photovoltaic module cuts the junction box through the laser positioning of the box-taking device 1 with a cutting accuracy of ±0.1 mm, and is conveyed to the frame removal mechanism 2 through the conveyor system 3. The frame removal mechanism 2 driven by hydraulic pressure peels the aluminum frame at an inclination angle of 18°, and the hydraulic driving pressure is 18 MPa. The conveyor system 3 conveys the waste photovoltaic module with the junction box and the 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 hot knife group 18 and a pressure sensor 19, wherein: the temperature control range of the constant temperature heating chamber 17 is 250°C to 450°C; the array hot knife group 18 is composed of a plurality of wedge-shaped blades with independent temperature control, and the surface of the blades is provided 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. The array hot knife group 18 cuts into the EVA adhesive layer of the waste photovoltaic module at 320°C and a pressure of 0.6MPa to separate 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 through the conveying system 3. The detection and separation device 5 includes a vacuum suction cup array 20, an electromagnetic sorting module 21, a CCD visual positioning system and an X-ray fluorescence spectrometer, wherein: the vacuum suction cup array 20 is composed of 32 independently controlled vacuum suction cups arranged in a 4×8 matrix, and a flexible silicone sealing ring is provided at the bottom of the suction cup. The CCD visual positioning system obtains the three-dimensional coordinate data of the silicon wafer through spectral imaging to identify the position of the silicon wafer, and accurately adsorbs the silicon wafer to the positioning groove of the silicon wafer conveyor belt of the conveying system 3 with a vacuum degree of -80kPa to -100kPa; the electromagnetic sorting module 21 adopts a Helmholtz coil structure to generate a 1.0T to 1.5T gradient magnetic field, and is equipped with a vibration screening mechanism with an amplitude of 0.5-1.2mm and a frequency of 15-25Hz, and is assisted by a pulse airflow of 1.5-2.5m / s to sort metal impurities with a particle size of 50-200μm; the X-ray fluorescence spectrometer is used to monitor the 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 port of the jaw crusher 6 through a pneumatic slide rail. The slide rail has an inclination angle of 15° and a polyurethane wear-resistant layer is laid on its surface. 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, and the working surfaces of the movable jaw plate 22 and the fixed jaw plate 23 are in a corrugated tooth structure, with a tooth height of 3-5 mm, a crushing chamber angle of 18-22°, and a gap of 8 mm between the movable jaw plate 22 and the fixed jaw plate 23 to crush the particles into 10±3 mm particles. The silicon wafers are transported to the jaw crusher 6 through the conveying system 3, and the silicon wafers are crushed to a diameter of D=10 mm 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 pipeline. The inner wall of the pneumatic conveying pipeline is provided with a polytetrafluoroethylene coating. A particle size detector is installed in the middle of the pipeline. When the particle size is detected to be greater than 15mm, 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 transported to the silver extractor 7 through a pneumatic conveying pipeline to extract the silver electrodes in the silicon wafers. The silver extractor 7 uses a high-voltage electrostatic-vortex current composite separation method, with a voltage of 28 kV and a magnetic roller rotation speed of 1800 rpm, and the removal rate of lead impurities is greater than 98.5%;

[0044] The discharge port of the silver extractor 7 is connected to the feed bin of the ball mill 8 through a stainless steel pneumatic conveying pipeline with a diameter of Φ200 mm. The pipeline is equipped with a Venturi ejector with a working pressure of 0.25 MPa and a three-way diverter valve with a switching response time < 0.5 s to achieve the directional transportation of silicon powder and the diversion of impurities. There are two ball mills 8 in total, and the two ball mills 8 are connected in sequence through a stainless steel pneumatic conveying pipeline. The silicon wafers from which the silver electrodes have been extracted are transported to the ball mill 8 by the conveying system 3. The silicon wafers and the carbon source are mixed according to a mass ratio of 1:0.3, and ball milled for 4 hours under argon protection to obtain a silicon-carbon composite powder with D < 10 μm;

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

[0046] The ball mill 8 is equipped with an in-situ atmosphere control system. The system includes an argon replacement unit, a temperature monitoring module, and a cooling jacket. Among them: The argon replacement unit is a porous gas distributor at the top of the grinding tank of the ball mill 8, and high-purity argon is continuously introduced into the grinding tank at a flow rate of 5 - 15 L / min through the porous gas distributor at the top of the grinding tank to maintain the oxygen content inside the grinding tank below 50 ppm; The temperature monitoring module is composed of an infrared thermal imaging camera array arranged around the outer wall of the grinding tank, which real-time monitors the surface temperature distribution of the tank body at a sampling frequency of 20 frames per second and feeds the temperature data back to the central control system 16; The cooling jacket uses a double-layer stainless steel sleeve structure to cover the grinding tank, and an ethylene glycol aqueous solution with a temperature ranging from -10°C to 5°C circulates inside the jacket. By adjusting the solution flow rate, the working temperature of the grinding tank is stabilized within the range of 25 ± 5°C;

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

[0048] The spray drying tower 13 is connected to the Joule heating device 14 through 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. Among them: The feeding system 24 has functions of automatic feeding, automatic stirring, and weighing feedback; The integrated electrode sintering system 25 sinters the dried silicon-carbon composite powder at a sintering temperature of 500°C - 2000°C under argon protection to form a uniform carbon coating layer with a thickness of 20 - 40 nm on the silicon surface; The inert atmosphere control device 27 dynamically adjusts the atmosphere according to the detection results; The cooling and discharging system 26 is used to cool the sintered silicon-carbon negative electrode and send it to the aggregate box;

[0049] A specific surface area tester is provided at the feed inlet of the Joule heating system 14 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 of the array type hot knife group 18 (±3%) and the sintering temperature inside the electrode sintering system 25 (±5°C) to obtain a first charge-discharge efficiency of the silicon-carbon negative electrode > 90% and a capacity retention rate of > 89% after 500 cycles at 1C;

[0050] The spray drying tower 13 is coupled with the hot air circulation pipeline 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 with a pulse dust collector 9 through a pipeline. When the vacuum chuck array 20 adsorbs the silicon wafer, the pulse dust collector 9 is triggered synchronously to collect lead dust under negative pressure. The air outlet of the pulse dust collector 9 is connected to the TO furnace 10 through a pipeline. The dust-removed flue gas is transported to the TO furnace 10, purified and heated by combustion. The exhaust port of the TO furnace 10 is connected to the air inlet of the hot knife separation module 4, and 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 group and a hot air circulation pipeline. Among them: The spiral heat exchange tube group is wound on the outer wall of the TO furnace 10, and the heat exchange efficiency is greater than 80%. The 400°C waste gas discharged from the TO furnace 10 is heat-exchanged through the spiral heat exchange tube group; A composite phase change heat storage body is filled in the interlayer of the TO furnace 10, filled with Al-Si alloy and NaNO3-KNO3 mixed salt. The phase change temperature of the Al-Si alloy is 580°C, and the phase change temperature of the NaNO3-KNO3 mixed salt is 220°C; The hot air circulation pipeline transports the medium-temperature gas of 300 - 400°C generated by the TO furnace 10 to the constant temperature heating cavity 17 inside the hot knife separation module 4, and then transports the low-temperature gas of 100 - 150°C 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 sequentially connected with an activated carbon adsorption box 11 and an induced draft fan 12 through a pipeline. Under the negative pressure generated by the induced draft fan 12, the waste 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 is connected to the pulse dust collector 9 and the activated carbon adsorption box 11 in series to achieve the up-to-standard discharge of dust and VOCs. The final single-line daily treatment capacity reaches 25 tons, and the tap density of the silicon-carbon anode is ≥1.2 g / cm 3 , and the comprehensive energy consumption is 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. Among them: the crushing particle size closed-loop control module dynamically adjusts the hydraulic pressure of the jaw crusher 6 according to the data of the particle size detector, and the control accuracy is ±0.1 MPa; the carbon doping optimization module automatically adjusts the carbon source addition ratio based on the feedback data of the specific surface area tester through the PID algorithm, and the adjustment resolution is ±0.5 wt%; 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] In this embodiment, a feedforward-feedback dual-channel control is constructed based on the existing PID algorithm. The feedforward channel predicts the optimal carbon source addition amount through an artificial neural network (ANN) based on the data of the specific surface area tester. The feedback channel uses an incremental PID algorithm to finely adjust the carbon source feeding speed in steps of 0.1 wt%, and introduces process constraint conditions. When the Fe content of the silicon powder is detected to be >200 ppm, the carbon source over-compensation mode (+0.3 wt%) is triggered to inhibit the catalytic side reaction of metal impurities.

[0056] Preferably, in the ball mill 8, the recycled silicon powder is dry-mixed with biomass carbon. The biomass carbon is coconut shell charcoal, and the specific surface area is 1200 m 2 / g.

[0057] Preferably, the conveying system 3 is provided with a stainless steel diversion groove. The inclination angle of the diversion groove is 12°, and the surface of the groove body is sprayed with a polytetrafluoroethylene coating with a thickness of 200 μm to prevent lead dust adhesion.

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

[0059] Preferably, the central control system 16 dynamically adjusts the pressing speed of the array type hot knife group 18 and controls it within 0.1 - 0.3 m / min to inhibit the generation of lead vapor.

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

[0061] Preferably, between the frame removal mechanism 2 and the hot knife separation module 4 of the conveying system 3, a 40kHz ultrasonic cleaning tank is additionally provided. The material enters the ultrasonic cleaning tank through the concave conveyor belt, and the PET protective layer is removed by isopropyl alcohol with a combined concentration of 25%.

[0062] In this embodiment, the lead removal rate in waste photovoltaic modules is increased by 40% compared with the traditional process, meeting the lead content standard (<10ppm) of GB / T30882-2014 "Silicon Materials for Electronic Industry". Moreover, the waste heat recycling reduces the energy consumption in the separation section by 52%.

[0063] Preferably, when co-processing electronic waste, the roller of the conveying system 3 can be additionally provided with a double helix mixing bin with an adjustable rotation speed of 15 - 25rpm. The waste circuit board powder (D50 = 15μm) and silicon powder are evenly mixed at a mass ratio of 1:1.5. The mixed material enters the detection and separation device 5 through a pneumatic conveying pipeline with a diameter of Φ200mm and a ceramic inner lining. The electromagnetic separation module 21 is loaded with a 1.0T gradient magnetic field. The rotation speed of the magnetic roller is dynamically adjusted to 800 - 1200rpm and the separation gap is adjusted to 5 - 8mm through a programmable logic controller PLC to realize the online separation of copper and silver. The sorted silicon-based mixture enters the feeding system 24 of the Joule heating device 14. First, pyrolysis is performed at 450°C with an argon flow rate of 10L / min and a heat preservation time of 30min to remove organic substances. Then, alloying is carried out at 850°C, and a 3% hydrogen-argon mixed gas is introduced to perform a silicon-metal eutectic reaction. Then, granulation is carried out at 1250°C with an atomization pressure of 8MPa to prepare spherical particles with a diameter of 50 - 80μm. The integrated electrode sintering system 25 maintains the oxygen content <50ppm through the inert gas control device 27. The cooling and discharging system 26 uses nitrogen quenching, and the cooling rate of 50°C / min inhibits grain coarsening. Finally, a silicon-based alloy negative electrode is prepared, 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 set as a digital twin system, where: The central control system 16 integrates a real-time sensing network and an algorithm model. A high-precision wear sensor (accuracy ±0.005 mm) is installed on the arrayed hot knife group 18 of the hot knife separation module 4 to dynamically monitor the tool life and link with the deep learning model, and the error in predicting the hot knife replacement cycle is <3%; Multi-channel temperature probes with an error of ±2 °C are arranged in the TO furnace 10. Combining three-dimensional simulation to construct a digital mirror of the sintering temperature field to optimize the heating parameters in real time; The visualization interface dynamically displays the stress distribution of the jaw crusher 6, the atomization state of the spray drying tower 13, and the grinding ball loss rate of the ball mill 8, and synchronously marks the energy consumption heat map of key equipment (color temperature gradient marking); The system uses a multi-objective optimization algorithm to automatically generate a process plan (such as a hot knife pressure of 0.25 MPa and a sintering heating rate of 8 °C / min), and adjusts the parameters in real time through the industrial Internet of Things, increasing the production capacity by 40% to 2.1 tons per hour and reducing the product defect rate to 0.18% (meeting the IEC 62474 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, with an exhaust gas treatment efficiency >99% and the overall computing power load of the system <35%, meeting the requirements of the ISO 23247-3 digital twin standard.

[0065] Preferably, a spraying mechanism is provided inside the hot knife separation module 4. By spraying an ammonium bifluoride solution with a concentration of 3% and a pH of 4.5, the EVA adhesive layer is softened, thereby reducing the cutting pressure of the arrayed hot knife group 18 to 0.15 MPa and the temperature to 220 °C.

[0066] As Figure 4 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 used photovoltaic module first undergoes laser positioning by the box-taking device 1 to cut off the junction box, and then the aluminum frame is peeled off at an angle of 18° by the hydraulic-driven frame removal mechanism 2. It is sent into the hot knife separation module 4 by the conveyor system 3. The arrayed hot knife group 18 cuts into the EVA adhesive layer at a pressure of 0.6 MPa at 320 °C to separate the glass and the silicon wafer. The waste gas generated by the hot knife separation module 4 is transported to the pulse dust collector 9 to remove silicon-containing dust. The waste gas after dust removal by the pulse dust collector 9 enters the TO furnace 10, and medium-temperature gas at 300 - 400 °C is generated through pyrolysis. The medium-temperature gas enters the hot knife separation module 4 to heat the inside of the constant-temperature heating cavity 17 to 300 °C;

[0068] Step 2: The silicon wafer and the glass are sent to the detection and separation device 5 through the conveyor system 3. The detection and separation device 5 identifies the position of the silicon wafer through multispectral imaging and monitors the cadmium and tellurium contents in real time through an X-ray fluorescence spectrometer. When the contents reach the set threshold, the vacuum chuck array 20 is triggered to isolate the contaminated materials, and the heavy metal residue of the silicon powder is <3 ppm. Otherwise, the vacuum chuck array 20 picks up the silicon wafer to the pneumatic slide rail, and the electromagnetic separation module 21 separates 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, and then sent to the silver extractor 7 to extract the silver electrode. After the silver electrode is extracted by the silver extractor 7, the silicon wafer enters the ball mill 8. Under the protection of argon, the loss-in-weight feeder of the ball mill 8 inputs carbon nanotubes into the ball mill 8 according to the 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 h to obtain a 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 - 50 μm. The particles enter the Joule heating device 14. The purity of argon in the Joule heating system 14 is greater than 99.99%. It adopts a stepwise heating strategy to preheat at 500 °C first and then sinter at 1200 °C to form a uniform carbon coating layer of 20 - 40 nm on the silicon surface, and then slowly cools. The finished silicon-carbon anode material with a lead residue of less than 5 ppm is output through the nitrogen sealing channel (oxygen content less than 50 ppm) of the cooling and discharging system 26;

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

[0072] Application Example 1

[0073] Retired photovoltaic modules enter the pretreatment section through an automated conveyor line. The box-taking device 1 locates the junction box through a vision system. After precisely cutting it with a hydraulic shear head with a pressure of 0.3 MPa, the four groups of servo jaws of the frame removal mechanism 2 cooperate with a rotary breaking head with a torque of 2000 N·m to peel off the aluminum frame within 30 seconds, and the recovery rate of the aluminum frame is 99.2%); The pretreated modules enter the hot knife separation module 4 through the conveyor system 3. The array of hot knives 18 inserts into the layer at a speed of 0.1 mm / s and a constant temperature of 380 °C with wedge-shaped blades. The pressure sensor dynamically adjusts the pressure at 0.5 - 1.0 MPa to achieve micron-level delamination of the glass / silicon wafers. The separated silicon wafers are sucked by the vacuum suction cup array 20 and sent into the jaw crusher 6. The corrugated tooth-shaped moving jaw plate 22 crushes the silicon wafers into particles of 15 - 20 mm at a pressure of 25 MPa and a chamber angle of 22°. The crushing efficiency is 3 tons per hour. The crushed material enters the silver extraction machine 7 through a pneumatic pipeline with a PTFE lining, and the silver electrode is recovered through an electrostatic-magnetic separation composite process, with a recovery efficiency > 98%); The silicon powder after silver extraction enters the ball mill 8. Using three-stage silicon carbide grinding balls of 5 mm, 8 mm, and 10 mm, a ball-to-material ratio of 10:1, adding a straw carbon source with an ash content of less than 5%, and grinding for 12 hours at a speed of 480 rpm. The cooling jacket of the ball mill 8 is filled with -5 °C ethylene glycol to control the temperature ≤ 20 °C, producing a silicon-carbon composite powder with a particle size of 2.5 μm. After the powder is granulated by the spray drying tower 13, it enters the Joule heating device 14 and is sintered at 1000 °C to obtain the silicon-carbon negative electrode material;

[0074] The activated carbon adsorption box 11 purifies the tail gas discharged from the spray drying tower 13, making the total non-methane hydrocarbons less than 12 mg / m 3 , meeting GB 30484. The waste heat recovery system 15 supplies the 400 °C waste heat generated by the TO furnace 10 to the hot knife module 4, and the 100 °C waste heat generated by the waste heat supply to the hot knife module 4 is used for the spray drying tower 13;

[0075] In the above process, the central control system 16 dynamically regulates the jaw spacing and carbon doping. Among them, the XRF verifies that the carbon content is 10 ± 0.3 wt%. The obtained silicon-carbon negative electrode material is used for power batteries, with an initial charge-discharge efficiency of 89.5% and a 100-cycle capacity retention rate of 91% at 0.5 C, meeting the power battery standard of GB / T 36276-2018.

[0076] Application Example 2

[0077] In the production of silicon-carbon anodes, a jaw crusher 6 performs laminated crushing with corrugated tooth profiles between a moving jaw plate 22 and a fixed jaw plate 23, where: the hydraulic pressure is 25 ± 0.5 MPa, the water-cooling system has ΔT < 10 °C, silicon particles with D50 = 20 ± 2 mm are produced, and through a 150-mm silicon nitride-coated pneumatic pipeline, they are quantitatively transported to a ball mill 8 at a wind speed of 2.8 m / s. Meanwhile, an 8.0 wt% pre-treated carbon source is added by a loss-in-weight feeder with an accuracy of ±0.05%. The pre-treated carbon source is obtained by hydrochloric acid activation - water washing - pre-carbonization at 800 °C of waste newspapers, resulting in a carbon source with an ash content not exceeding 2.7%. The ball mill 8 starts an argon replacement procedure, with its top-mounted annular distributor introducing 99.999% argon at 12 L / min, and a vacuum pump exhausting at -0.08 MPa. The oxygen content drops to 35 ppm within 15 min. Three-stage silicon carbide grinding balls of 5 mm, 8 mm, and 10 mm are used, with a volume ratio of 3:5:2 and a ball-to-material ratio of 12:1. Mechanical alloying is carried out at 480 rpm. The central control system 16 dynamically regulates the flow rate of -5 °C ethylene glycol in the cooling jacket (PID control 8 m 3 / h) through an infrared thermal imager with a resolution of 0.1 °C to maintain a grinding temperature of 55 ± 3 °C for 8 h to obtain a composite powder with D50 = 1.8 ± 0.2 μm; the slurry is transported to a blending tank by a screw pump (shear rate of 1200 s-1), and 0.8 wt% CMC (degree of substitution 0.7) and 0.2 wt% SDBS are added. An on-line rheometer is used to adjust it to a solid content of 35.0 ± 0.3%, a viscosity of 120 ± 15 mPa·s (25 °C), and a Zeta potential of -35 ± 2 mV; the heat recovered by the waste heat recovery system 15 enters the spray drying tower 13 at 160 °C. Through waste heat recovery, the energy consumption of the drying tower 13 is reduced by 27%. Then, the inside of the spray drying tower 13 is heated to 200 ± 3 °C, and spherical particles with D50 = 40 ± 3 μm are granulated by an atomizing disk with a pressure of 4.5 MPa and a speed of 22000 ± 200 rpm. Their tapped density is 1.85 ± 0.05 g / cm 3 ; the Joule heating device 14 performs gradient sintering, 500 °C / 1.5 h stress release (XRD full width at half maximum drops by 40%) → 1200 °C / 4 h carbothermal reduction (H / Ar mixed gas, reaction formula SiO + 3C → β-SiC + 2CO↑), slow cooling, to obtain the silicon-carbon anode material;

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

[0079] The comprehensive energy consumption of this application example is 11.5 kWh / kg, meeting GB / T 23331-2020, and the energy consumption is reduced by 37.8% compared with the traditional process.

[0080] Application Example 3

[0081] After the retired photovoltaic modules have their junction boxes removed by laser cutting using the junction box removal device 1, the frame removal mechanism 2 peels off the aluminum frame through a hydraulic shearing mode at a pressure of 20 MPa. The conveying system 3 feeds the modules into the hot knife separation module 4 at a speed of 0.8 m / s. The array of hot knives 18 maintains a temperature of 320 ± 5 °C in the constant temperature heating cavity 17. The pressure sensor 19 adjusts the downward pressure of the blades in real time to 0.6 - 0.8 MPa to achieve non-destructive delamination of the glass and silicon wafers. The separated silicon wafers are adsorbed and positioned by the vacuum chuck array 20 of the detection and separation device 5. The electromagnetic sorting module 21 sorts metal impurities at a magnetic field intensity of 1.2 T, and the recovery rates of copper and silver are 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 particles of 10 ± 3 mm with a corrugated tooth shape structure with a tooth height of 5 mm and a crushing cavity angle of 18°. The crushed material is transported through a pneumatic pipeline with a polytetrafluoroethylene coating on the inner wall to the silver extraction machine 7, and the silicon powder is further purified by high-voltage electrostatic separation at 25 kV to make the silver residue less than 0.03%. The silicon powder after silver extraction enters the ball mill 8, using three-stage silicon carbide grinding balls of 5 mm, 8 mm, and 10 mm, with a ball-to-material ratio of 12:1, and is ground for 8 hours under argon protection (i.e., the inert atmosphere control device 27 maintains the oxygen content less than 50 ppm). The temperature of the tank body is regulated by the waste heat recovery system 15, with a fluctuation of < ±3 °C. The ball mill product is atomized by hot air at 200 °C in the spray drying tower 13, and the atomizing disk rotates at a speed of 22,000 rpm to form a silicon-carbon composite powder with a particle size of 20 - 50 μm. Subsequently, it enters the integrated electrode sintering system 25 of the Joule heating device 14 and performs step sintering in an argon atmosphere: preheating at 500 °C → carbon coating at 1200 °C → rapid cooling with nitrogen in the cooling and discharging system 26 to obtain the silicon-carbon negative electrode material;

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

[0083] The obtained silicon-carbon negative electrode material is used in power batteries, with a first charge-discharge efficiency of 91%, a capacity retention rate of 89% after 500 cycles at 1C, and a tap density of 1.25 g / cm 3 , meeting the GB / T 36276-2018 standard.

Claims

1. A production device for silicon-carbon anode materials based on hot knife separation and waste heat recycling, characterized in that, It includes a central control system (16), as well as a box-taking device (1), a frame removal mechanism (2), a hot knife separation module (4), and a detection and separation device (5) that are sequentially connected through a conveying system (3). The detection and separation device (5) is connected to the feed inlet of a jaw crusher (6) through a pneumatic slide rail. The discharge outlet of the jaw crusher (6) is connected to the feed inlet of a silver extraction machine (7) through a pneumatic conveying pipeline. The discharge outlet of the silver extraction machine (7) is connected to the feed bin of a ball mill (8) through a pneumatic conveying pipeline. The discharge outlet of the ball mill (8) is connected to a spray drying tower (13) through a screw feeder. The spray drying tower (13) is connected to a Joule heating device (14) through a conveying pipeline. And the exhaust outlet of the spray drying tower (13) is sequentially connected with an activated carbon adsorption box (11) and an induced draft fan (12) through a pipeline; The hot knife separation module 4 includes a constant temperature heating cavity (17), an array type hot knife group (18), and a pressure sensor (19). Both the array type hot knife group (18) and the pressure sensor (19) are connected to the central control system (16); The detection and separation device (5) includes a vacuum suction cup array (20), an electromagnetic separation module (21), a CCD vision positioning system, and an X-ray fluorescence spectrometer for real-time monitoring of the cadmium and tellurium contents. The X-ray fluorescence spectrometer, the CCD vision positioning system, the electromagnetic separation module (21), and the vacuum suction cup 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 recycling according to claim 1, wherein It also includes a pulse dust collector (9), a TO furnace (10), and a waste heat recovery system (15); The pulse dust collector (9) is connected to the exhaust smoke outlet of the hot knife separation module (4) through a pipeline. The air outlet of the pulse dust collector (9) is connected to the air inlet of the TO furnace (10) through a pipeline. The air outlet of the TO furnace (10) is connected to the air inlet of the hot knife separation module (4); The waste heat recovery system (15) includes a spiral heat exchange tube group and a hot air circulation pipeline. The spiral heat exchange tube group is wound on the outer wall of the TO furnace (10). The hot air circulation pipeline is connected to the constant temperature heating cavity (17).

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

4. The silicon-carbon anode material production equipment based on hot knife separation and waste heat reuse according to any one of claims 1 to 3, characterized in that, The array type hot knife group (18) is composed of multiple groups of wedge-shaped blades with independent temperature control. The surface of the blades is provided with a nano-ceramic coating.

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

6. The production equipment for silicon-carbon anode materials based on hot-knife separation and waste heat recycling according to any one of claims 1 to 3, characterized in that, The jaw crusher (6) is hydraulically driven. The working surfaces of its moving jaw plate (22) and fixed jaw plate (23) are in a corrugated tooth-shaped structure, and the tooth height of the corrugated tooth-shaped structure is 3 - 5 mm; The included angle of the crushing cavity between the jaw plates (22) and the fixed jaw plate (23) is 18 - 22°.

7. The production equipment for silicon-carbon anode materials based on hot knife separation and waste heat recycling according to any one of claims 1 to 3, characterized in that, The pneumatic conveying pipeline is made of stainless steel, and a polytetrafluoroethylene coating is applied to the inner wall of the pneumatic conveying pipeline; and a particle size detector is installed in the middle section of the pneumatic conveying pipeline for connecting the jaw crusher (6) and the silver extraction machine (7). The particle size detector is connected to the central control system (16).

8. The production equipment for silicon-carbon anode materials based on hot-knife separation and waste heat recycling 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 replacement unit, a temperature monitoring module, and a cooling jacket. Specifically: The argon replacement unit is a porous gas distributor arranged at 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 production equipment for silicon-carbon anode materials based on hot-knife separation and waste heat recycling according to any one of claims 1 to 3, characterized in that, A weighing module is arranged at the discharge port of the ball mill (8), 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 reuse of the device according to claim 2, characterized in that, It includes the following steps: Step 1: The waste photovoltaic module first has its junction box cut off by the box-taking device (1), then the aluminum frame is peeled off by the frame removal mechanism (2), and then it 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 under a pressure of 0.6 MPa to separate the glass and the silicon wafer. The waste gas generated by the hot knife separation module (4) is transported to enter the pulse dust collector (9). The pulse dust collector (9) is used to remove the silicon-containing dust in the waste gas. The waste gas after being dusted 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) to heat the inside of the constant-temperature heating cavity (17) to 300 °C. Step 2: The silicon wafer and the glass are sent to the detection and separation device (5) by the conveying system (3). The CCD vision positioning system identifies the position of the silicon wafer through multi-spectral imaging and real-time monitors the cadmium and tellurium contents through the X-ray fluorescence spectrometer. When it reaches the set threshold, the vacuum chuck array (20) is triggered to isolate the contaminated materials. Otherwise, the vacuum chuck array (20) picks up the silicon wafer and transports it to the pneumatic slide rail; meanwhile, the electromagnetic separation module (21) separates metal impurities and lead-containing solder strip fragments with a gradient magnetic field of 1.0 T - 1.5 T. Step 3: The pneumatic slide rail transports the separated silicon wafers to the jaw crusher (6), where they are crushed to D = 10 ± 3 mm and then transported to the silver extraction machine (7) by the pneumatic conveying pipeline to extract the silver electrodes. Then the silicon wafers enter the ball mill (8). Under argon protection, a carbon source is put into the ball mill (8) according to the mass ratio of silicon powder to carbon source of (0.2 - 1):

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

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