A graphite impurity detection system and a detection method thereof

Abstract

This invention provides a graphite impurity detection system and method. The system includes: a gas-thermal coupled high-temperature purification reaction module, an air intake control unit, a full-temperature-range segmented online detection module, and an intelligent terminal. The full-temperature-range segmented online detection module includes a first branch, a second branch, and a third branch. The first branch is equipped with a low-temperature organic matter detection unit, the second branch is equipped with a medium-temperature volatile impurity detection unit, and the third branch is equipped with a high-temperature non-volatile matter and halide detection unit. By setting up multiple branch flow paths and soft-switching valve timing control, this application successfully achieves targeted stripping detection of complex impurities. This allows organic impurities resolved in the low-temperature zone, volatile alkali metals desorbed in the medium-temperature zone, and refractory metals and halides that break through the crystal lattice in the high-temperature zone to independently enter the most suitable detection unit, significantly improving the sensitivity and specificity of impurity detection in different temperature zones.

Description

Technical Field

[0001] This application relates to the field of carbon-based material purification mechanism testing and characterization technology, specifically to a graphite impurity detection system and its detection method. Background Technology

[0002] High-purity graphite, due to its excellent electrical and thermal conductivity and chemical stability, plays an irreplaceable role in high-end manufacturing fields such as lithium-ion battery anodes, semiconductor single-crystal growth thermal field materials, and nuclear graphite for nuclear reactors. Whether in the deep processing and purification of natural graphite or the resource recycling of decommissioned waste graphite, extremely stringent high-temperature gas thermal purification or high-temperature halogenation purification processes are required. Under the action of a high-temperature thermal field, supplemented by halogen reactive gases, the complex impurity system inside graphite (including residual organic binders, low-boiling-point alkali metal ions, and high-boiling-point transition metal elements) undergoes a complex multiphase physicochemical evolution process, including solid-phase diffusion, surface precipitation, and gas-phase escape.

[0003] Currently, industry research on the mechanism and effectiveness evaluation of high-temperature graphite purification processes mainly relies on offline detection technology, which involves extracting and detecting the solid graphite residue at the final stage of the reaction. The conventional approach is to extract the final solid graphite residue after the purification process is complete and the furnace has cooled to room temperature, then use X-ray diffractometer or inductively coupled plasma mass spectrometry to determine its microstructure and elemental content. However, this offline detection only obtains static data on impurities in the initial and final states, losing information on the dynamic evolution of impurities under ultra-high temperature conditions. This leads to the optimization of purification process parameters often relying on trial and error. The removal of impurities during graphite purification exhibits a temperature-gradient release characteristic. In existing single-flow-path or single-point observation systems, tar-like organic matter precipitated in the low-temperature zone and heavy metals precipitated in the high-temperature zone are highly susceptible to severe cross-contamination and signal interference.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] To address one of the aforementioned technical problems, this application provides a graphite impurity detection system and method thereof.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, embodiments of this application provide a graphite impurity detection system, comprising:

[0008] A gas-thermal coupling high-temperature purification reaction module includes a micro fixed-bed purification furnace. The micro fixed-bed purification furnace has a furnace cavity inside and is provided with an air inlet and an air outlet, both of which are connected to the furnace cavity.

[0009] An intake control unit is connected to the air intake port;

[0010] A full-temperature-range segmented online detection module is provided, wherein the input end of the full-temperature-range segmented online detection module is connected to the air outlet, and the full-temperature-range segmented online detection module includes a first branch, a second branch and a third branch. Valves and heat tracing layers are provided on the first branch, a low-temperature organic matter detection unit is provided on the first branch, a medium-temperature volatile impurity detection unit is provided on the second branch, and a high-temperature non-volatile matter and halogenation detection unit is provided on the third branch.

[0011] The intelligent terminal is electrically connected to each of the valves to control the opening and closing of each valve.

[0012] Optionally, a Venturi tube section is provided on the third branch, and the Venturi tube section is located between the third valve and the high-temperature non-volatile substances and halides detection unit;

[0013] An absorption port is provided at the narrowing section of the venturi tube, and the absorption port is connected to a cold absorption liquid source.

[0014] Optionally, the graphite impurity detection system includes an exhaust gas treatment module;

[0015] The ends of the first branch, the second branch, and the third branch are all connected to the exhaust gas treatment module;

[0016] The exhaust gas treatment module includes a cryogenic trap, an alkaline gas scrubbing device, and a porous activated carbon adsorption device arranged in sequence.

[0017] Optionally, the low-temperature organic matter detection unit includes a gas chromatography-mass spectrometry system or a Fourier transform infrared spectrometer;

[0018] The medium-temperature volatile impurity detection unit includes an ultraviolet-visible spectrometer, and the detection end of the ultraviolet-visible spectrometer is connected in series with an online gas flow cell with a heated quartz window.

[0019] The high-temperature non-volatile and halide detection unit includes a liquid phase combined analysis system consisting of an ion chromatograph and an inductively coupled plasma mass spectrometer.

[0020] Optionally, the graphite impurity detection system includes an offline multi-scale characterization module, which is used to evaluate the microstructure and quantitatively analyze trace impurities in the purified solid residue.

[0021] The offline multi-scale characterization module includes at least one of a confocal Raman spectrometer, a high-resolution X-ray diffractometer, a field emission scanning electron microscope, and an inductively coupled plasma atomic emission spectrometer.

[0022] Optionally, the graphite impurity detection system includes an in-situ ultra-high temperature optical detection module, which includes a multi-channel wide-spectrum instrument and a high-temperature resistant fiber array. One end of the high-temperature resistant fiber array is connected to the multi-channel wide-spectrum instrument, and the other end is connected to the observation port on the micro fixed bed purification furnace.

[0023] Optionally, the gas-thermal coupling high-temperature purification reaction module includes a loading crucible;

[0024] The loading crucible can be accommodated within the furnace cavity;

[0025] The micro fixed-bed purification furnace is provided with a lower observation hole and an upper observation hole, both of which are connected to the furnace cavity. The extension line of the lower observation hole passes through the upper surface of the loading crucible, and the extension line of the upper observation hole passes through the top area of ​​the loading crucible.

[0026] The high-temperature resistant fiber array includes a first optical path and a second optical path, the first optical path extending to the lower observation aperture and the second optical path extending to the upper observation aperture.

[0027] Secondly, this application provides a detection method for the above-mentioned graphite impurity detection system, comprising the following steps:

[0028] S1. Load the waste graphite material to be tested into the micro fixed bed purification furnace, introduce high-purity inert carrier gas at a preset flow rate through the air intake control unit, exhaust the air in the system, start the in-situ ultra-high temperature optical detection module, and initialize and calibrate the baseline of each detection instrument through the intelligent terminal.

[0029] S2. In the low-temperature organic matter analysis stage, the first branch is turned on and the second and third branches are turned off simultaneously. The micro fixed bed purification furnace is controlled to heat from room temperature to 300°C at a first heating rate of 5°C / min and is kept at a constant temperature for 30min. The binder and residual electrolyte precipitated in the waste graphite material to be tested enter the low-temperature organic matter detection unit through the first branch with the carrier gas for online component identification and tracking.

[0030] S3, in the intermediate-temperature volatile impurity analysis stage, the intelligent terminal triggers a soft switching logic to open the second branch and disconnect the first branch, controlling the micro fixed-bed purification furnace to heat to 1000℃ at a second heating rate of 5℃ / min, and maintain the temperature for 30min; the gaseous volatile metals escaping from the waste graphite material to be tested enter the intermediate-temperature volatile impurity detection unit for dynamic concentration monitoring.

[0031] S4. During the high-temperature non-volatile impurity analysis stage, the soft switching logic is triggered to open the third branch and simultaneously close the second branch. The heat tracing layer on the third branch is activated, and the micro fixed bed purification furnace is controlled to heat up to the third set temperature range of 1800℃ at a third heating rate of 5℃ / min. During this stage, the in-situ ultra-high temperature optical detection module continues to operate, and the non-volatile impurities that are vaporized and precipitated enter the high-temperature non-volatile substances and halides detection unit for online measurement.

[0032] S5. In the multi-field coupled halogenation purification stage, keep the third branch open and introduce halogen reaction gas into the micro fixed bed purification furnace under isothermal conditions of 1800℃. Maintain the reaction for 30 minutes. Monitor the jump point and attenuation tail of the metal halide charge ratio signal in the high-temperature non-volatile and halide detection unit in real time. When the signal returns to the baseline, it is determined that the halogenation elution equilibrium reaction has been completed.

[0033] S6. In the cooling and data fusion stage, the halogen reaction gas is cut off, and the system is naturally cooled to room temperature under the protection of inert carrier gas. The solid residue of the purified waste graphite material to be tested is taken out, and its crystal interlayer spacing evolution and the residual amount of ultimate trace impurities are determined by the offline multi-scale characterization module. Finally, the intelligent terminal performs spatiotemporal correlation and alignment of the in-situ spectral data, online segmented detection data and offline characterization data, thereby effectively reconstructing the complete migration and transformation mechanism and evolution model map of various impurities in the waste graphite material to be tested from "solid phase desorption and precipitation - gas phase transformation and migration - final solid phase residue".

[0034] Optionally, in steps S2-S5, the in-situ ultra-high temperature optical detection module uses the lower observation hole to collect the thermal radiation signal of the material bed surface to monitor the temperature fluctuation and physical state of the solid surface in real time, and uses the upper observation hole to capture the characteristic bright line spectrum emitted when metal atoms volatilize and escape; the intelligent terminal timestamps the temperature time series data inverted by the lower observation hole and the atomic emission characteristic peak data resolved by the upper observation hole, so as to realize the in-situ dynamic tracking of the migration and evolution process of impurities from solid to gas phase without destroying the gas dynamic flow field in the furnace.

[0035] Optionally, in steps S3 and S4, during pipeline switching, the intelligent terminal controls the valve to be opened to be in a gradual slow-opening state and the valve to be closed to be in a gradual slow-closing state. It also uses a pressure sensor installed in the gas-thermal coupling high-temperature purification reaction module to provide real-time feedback of the furnace pressure signal and dynamically adjusts the opening compensation value of the two valves in a closed loop to maintain the gas pressure fluctuation amplitude inside the reaction zone to be less than ±0.5 kPa, ensuring a smooth transition between the carrier gas flow field and the spectral detection signal.

[0036] By adopting the above technical solution, this application achieves the following beneficial effects:

[0037] This application successfully achieves targeted stripping detection of complex impurities by setting up multi-branch flow paths and soft-switching valve timing control. This allows organic impurities resolved in the low-temperature zone, volatile alkali metals desorbed in the medium-temperature zone, and refractory metals and halides that break through the crystal lattice in the high-temperature zone to enter the most suitable detection unit independently, significantly improving the sensitivity and specificity of impurity detection in different temperature zones.

[0038] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0039] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0040] Figure 1 This is a schematic diagram of the main cross-sectional structure of the gas-thermal coupling high-temperature purification reaction module provided in an embodiment of the present invention;

[0041] Figure 2 This is a side cross-sectional view of the gas-thermal coupling high-temperature purification reaction module provided in an embodiment of the present invention.

[0042] Figure 3 This is a partially enlarged cross-sectional view of the in-situ observation hole provided in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the overall structure of the detection system provided in an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of the full-temperature-range segmented online detection module provided in an embodiment of the present invention;

[0045] Figure 6 Line graph showing the program control and valve timing switching logic of the detection method provided in this embodiment of the invention as a function of time-temperature change.

[0046] Label Explanation:

[0047] Gas-heat coupled high-temperature purification reaction module 1, micro fixed-bed purification furnace 11, waste graphite material 111, loading crucible 112, feed inlet 113, discharge outlet 114, horizontal guide rail 115, quick-release water-cooled flange 116, gas inlet control unit 12, first inlet 121, second inlet 122, gas outlet 123, air distribution plate 124, lower observation hole 13, upper observation hole 14, ultra-high temperature resistant lens 151, dustproof glass lens 152, annular gas distribution ring 16, pressure sensor 17, furnace body heating layer 181, composite thermal insulation layer 182, furnace body protective layer 183, inert gas source 191, halogen gas source 192, cold absorption liquid source 193; In-situ ultra-high temperature optical detection module 2, multi-channel wide spectrum instrument 21, high-temperature resistant fiber optic array 22; Full-temperature range segmented online detection module 3. High-temperature three-way flow path assembly 31, first branch 311, second branch 312, third branch 313, first valve 321, second valve 322, third valve 323, first constant temperature heat tracing layer 331, second constant temperature heat tracing layer 332, ultra-high temperature corrosion-resistant heat tracing layer 333, inert quartz liner 334, low-temperature organic matter detection unit 341, medium-temperature volatile impurity detection unit 342, high-temperature non-volatile matter and halide detection unit 343, Venturi tube section 35; exhaust gas treatment module 4, cryogenic trap 41, alkaline gas washing device 42, porous activated carbon adsorption device 43; offline multi-scale characterization module 5, confocal Raman spectrometer 51, high-resolution X-ray diffractometer 52, field emission scanning electron microscope 53, inductively coupled plasma atomic emission spectrometer 54; smart terminal 6.

[0048] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0050] In the description of this invention, it should be noted that the terms "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] Example 1

[0053] Combination Figures 1 to 6 As shown in the illustration, this application provides a detailed description of a graphite impurity detection system, which includes: a gas-thermal coupled high-temperature purification reaction module 1, an air inlet control unit 12, a full-temperature-range segmented online detection module 3, and a smart terminal 6. The gas-thermal coupled high-temperature purification reaction module 1 includes a miniature fixed-bed purification furnace 11, which has a furnace cavity. The miniature fixed-bed purification furnace 11 has an air inlet and an air outlet 123, both of which are connected to the furnace cavity. The air inlet control unit 12 is connected to the air inlet. The input terminal of the full-temperature-range segmented online detection module 3 is connected to the air outlet 123. The full-temperature-range segmented online detection module 3 includes a first branch 311, a second branch 312, and a third branch 313. Valves and heat tracing layers are provided on the first branch 311, the second branch 312, and the third branch 313. The temperature on the first branch 311, the second branch 312, and the third branch 313 can increase progressively. A low-temperature organic matter detection unit 341 is provided on the first branch 311, a medium-temperature volatile impurity detection unit 342 is provided on the second branch 312, and a high-temperature non-volatile matter and halogenation detection unit 343 is provided on the third branch 313. The intelligent terminal 6 is electrically connected to each of the valves to control the opening and closing of each valve.

[0054] This application successfully achieves targeted stripping detection of complex impurities by setting up multi-branch flow paths and soft-switching valve timing control. This allows organic impurities resolved in the low-temperature zone, volatile alkali metals desorbed in the medium-temperature zone, and refractory metals and halides that break through the crystal lattice in the high-temperature zone to enter the most suitable detection unit independently, significantly improving the sensitivity and specificity of impurity detection in different temperature zones.

[0055] Combination Figure 5As shown, the full-temperature-range segmented online detection module 3 is the core structure for segmented detection of impurities in different temperature zones in this application. It includes a high-temperature three-way flow path assembly 31, the inlet of which is connected to the outlet 123 of the micro fixed-bed purification furnace 11 via a corrosion-resistant flange. The high-temperature three-way flow path assembly 31 branches out in parallel along the airflow direction into a first branch 311, a second branch 312, and a third branch 313. The pipe diameter of each branch is preferably a 1 / 8-inch to 1 / 2-inch compression fitting, and the material is 316L stainless steel or Hastelloy (for highly corrosive sections).

[0056] Among them, such as Figure 5 As shown, a first valve 321 is connected in series on the first branch 311, and its pipe is tightly covered with a first constant temperature heat tracing layer 331, preferably made of polyimide flexible heat tracing tape with built-in heating wire or aluminum silicate ceramic fiber heating jacket, maintaining the temperature at approximately 250°C. To prevent the adsorption of large molecular organic matter or tar at this stage, which could lead to a memory effect in the subsequent mass spectrometry detection, the inner wall of the first branch 311 is specially fitted with an inert quartz liner 334 whose surface has been chemically deactivated, to eliminate active adsorption sites on the pipe wall and prevent impurities from adhering. The end of the first branch 311 is connected to a low-temperature organic matter detection unit 341, preferably a GC-MS and FTIR coupled system.

[0057] A second valve 322 is connected in series on the second branch line 312. The pipe is covered with a second constant-temperature heating layer 332, similar in structure to the first constant-temperature heating layer 331, maintaining a temperature of 300-500℃. The end of the second branch line 312 is connected to a medium-temperature volatile impurity detection unit 342. The main analytical device of the medium-temperature volatile impurity detection unit 342 is preferably an ultraviolet-visible spectrometer (UV-Vis) or a tunable semiconductor laser spectrometer (TDLAS). Its sample inlet is equipped with a dedicated online gas flow cell. A heated quartz window is provided outside the online gas flow cell to prevent condensation of gaseous impurities, thereby achieving online detection of medium-boiling-point volatile impurities.

[0058] The third branch 313 is a high-temperature non-volatile and halide detection branch, connected in series with a third valve 323. The pipe is externally covered with an ultra-high temperature corrosion-resistant heat tracing layer 333, preferably a mineral-insulated armored heating cable with an Inconel alloy sheath, and an inner tube lined with Hastelloy alloy or silicon carbide ceramic. The end of the third branch 313 connects to a high-temperature non-volatile and halide detection unit 343, preferably a liquid chromatography combined analysis system consisting of an ion chromatograph (IC) and an inductively coupled plasma mass spectrometer (ICP-MS).

[0059] Understandably, during the ultra-high temperature halogenation stage (above 1800℃), the gas phase carries a large amount of highly corrosive metal halide vapors. If these vapors directly enter the high-temperature non-volatile substance and halide detection unit 343, they can easily cause severe damage to the detector. In this embodiment, a Venturi tube section is installed on the third branch 313. This Venturi tube section is located between the third valve 323 and the high-temperature non-volatile substance and halide detection unit 343. An absorption interface is installed at the narrowing part of the Venturi tube section 35, and the absorption interface is connected to the cold absorption liquid source 193. By using a corrosion-resistant polytetrafluoroethylene (PTFE) material for the internal Venturi tube structure design, the main channel is used to introduce high-temperature sample gas, and the external annular gap is connected to the cold absorption liquid source 193. When a high-temperature sample gas carrying corrosive halides flows through this area at high speed, creating negative pressure shear, the cold absorption liquid (such as ultrapure water or weakly alkaline buffer) pumped in from all sides quickly washes, quenches, and dissolves it into a safe room-temperature liquid phase ion sample, which is then transported to the downstream ICP-MS for ppt-level detection of trace heavy metal concentrations.

[0060] Optionally, such as Figure 4 and Figure 5 As shown, the graphite impurity detection system includes an exhaust gas treatment module 4. The ends of the first branch 311, the second branch 312, and the third branch 313 are all connected to the exhaust gas treatment module 4. The exhaust gas treatment module 4 includes a cryogenic trap 41, an alkaline gas scrubbing device 42, and a porous activated carbon adsorption device 43 arranged sequentially. After the low-temperature organic matter detection unit 341, the medium-temperature volatile impurity detection unit 342, and the high-temperature non-volatile matter and halide detection unit 343 complete non-destructive testing or diversion testing, the hazardous exhaust gas discharged is collected through a corrosion-resistant exhaust main pipe and connected to the exhaust gas treatment module 4. The exhaust gas treatment module 4 has the cryogenic trap 41, the alkaline gas scrubbing device 42, and the porous activated carbon adsorption device 43 connected in series along the airflow discharge direction. Through the above three-stage series treatment, the exhaust gas meets the emission requirements.

[0061] In some possible implementations, the low-temperature organic matter detection unit 341 includes a gas chromatography-mass spectrometry (GC-MS) instrument or a Fourier transform infrared (FTIR) spectrometer; the medium-temperature volatile impurity detection unit 342 includes a UV-Vis spectrometer, the detection end of which is connected in series with an online gas flow cell with a heated quartz window; and the high-temperature non-volatile matter and halide detection unit 343 includes a liquid chromatography-mass spectrometry (LC-MS) system composed of an ion chromatograph and an inductively coupled plasma mass spectrometer.

[0062] In some possible implementations, the graphite impurity detection system includes an offline multi-scale characterization module 5, which is used to evaluate the microstructure and quantitatively analyze trace impurities in the purified solid residue. The offline multi-scale characterization module 5 includes at least one of a confocal Raman spectrometer 51, a high-resolution X-ray diffractometer 52, a field emission scanning electron microscope 53, and an inductively coupled plasma atomic emission spectrometer 54.

[0063] In this embodiment, the offline multi-scale characterization module 5 is independent of the aforementioned fluid circulation system and includes four precision characterization devices for different physicochemical dimensions. Specifically, it may include a confocal Raman spectrometer 51, a high-resolution X-ray diffractometer 52, a field emission scanning electron microscope 53, and an inductively coupled plasma atomic emission spectrometer 54. The confocal Raman spectrometer 51 is used to determine the intensity ratio (ID / IG) of the D peak to the G peak of graphite to assess the repair of crystal defects and structural order. The high-resolution X-ray diffractometer 52 is used to calculate the interlayer spacing (d002) and crystallite size changes of graphite to characterize lattice relaxation and reconstruction evolution. The field emission scanning electron microscope 53 is used to visually observe the microstructure of the graphite surface and the removal of heterogeneous particles. The inductively coupled plasma atomic emission spectrometer 54 is used for high-precision absolute quantitative analysis of extremely small amounts (e.g., below ppm) of residual metallic impurities in the purification residue.

[0064] In some possible implementations, such as Figure 3 and Figure 4 As shown, the graphite impurity detection system includes an in-situ ultra-high temperature optical detection module 2, which includes a multi-channel wide spectrometer 21 and a high-temperature resistant fiber array 22. One end of the high-temperature resistant fiber array 22 is connected to the multi-channel wide spectrometer 21, and the other end is connected to the observation hole on the micro fixed bed purification furnace 11.

[0065] The in-situ ultra-high temperature optical detection module 2 includes a multi-channel wide spectrometer 21 and a high-temperature resistant fiber array 22. One end of the high-temperature resistant fiber array 22 is connected to the multi-channel wide spectrometer 21, and the other end is connected to the observation hole on the micro fixed bed purification furnace 11.

[0066] The in-situ ultra-high temperature optical detection module 2 is arranged in a safe, room-temperature area outside the micro fixed-bed purification furnace 11, and includes a multi-channel broadband spectrometer 21. The multi-channel broadband spectrometer 21 is connected to the external optical paths of the lower observation aperture 13 and the upper observation aperture 14 via multiple high-temperature resistant fiber arrays 22. The detection wavelength range of the multi-channel broadband spectrometer 21 preferably covers 200 nm to 1100 nm, enabling real-time acquisition and analysis of the thermal radiation and atomic emission characteristic peaks of different metallic impurities under different temperature gradients, thereby achieving in-situ tracking of the impurity release process without disrupting the flow field.

[0067] Specifically, the gas-thermal coupled high-temperature purification reaction module 1 includes a loading crucible 112, which can be accommodated in the furnace cavity. The micro fixed-bed purification furnace 11 is provided with a lower observation hole 13 and an upper observation hole 14, both of which are connected to the furnace cavity. The extension line of the lower observation hole 13 passes through the upper surface of the loading crucible 112, and the extension line of the upper observation hole 14 passes through the top region of the loading crucible 112. The high-temperature resistant fiber array 22 includes a first optical path and a second optical path. The first optical path extends to the lower observation hole 13, and the second optical path extends to the upper observation hole 14.

[0068] The intelligent terminal is preferably an industrial computer and PLC system equipped with proprietary algorithms, which is electrically connected to the sensors, flow meters, control valves, and detectors of the aforementioned modules via a bus. Specifically, the signals received by the intelligent terminal include: spectral radiation characteristic signals returned by the in-situ ultra-high temperature optical detection module 2, mass-to-charge ratio (m / z) and absorbance signals returned by the full-temperature-range segmented online detection module 3, micro-positive pressure feedback signals from the pressure sensor 17, and lattice defect data imported by the offline multi-scale characterization module 5. The intelligent terminal performs real-time analysis of the aforementioned multi-source heterogeneous data according to a preset algorithm and issues control commands to downstream actuators for adjusting heating power, shutting off flow path valves, and switching carrier gas mass flow rates, thereby achieving closed-loop automatic operation of the entire system.

[0069] Combination Figure 6 As shown in the embodiments of this application, a detection method for the above-mentioned graphite impurity detection system is also provided, including the following steps:

[0070] S1. Load the waste graphite material 111 to be tested into the micro fixed bed purification furnace 11, introduce high-purity inert carrier gas at a preset flow rate through the air intake control unit 12, exhaust the air in the system, start the in-situ ultra-high temperature optical detection module 2, and initialize and calibrate the baseline of each detection instrument through the intelligent terminal.

[0071] In this step, during loading and system initialization, the waste graphite material 111 to be tested is placed in the loading crucible 112 and pushed into the homogenization zone of the micro fixed-bed purification furnace 11 through the feed inlet 113, and the flange is locked. The intelligent terminal controls the gas inlet control unit 12, so that the inert gas source 191 (preferably high-purity argon) is introduced through the first inlet 121 at a preset flow rate. The gas flows through the gas outlet 123 and the online detection pipeline to purge the background air. The intelligent terminal adjusts the valve opening through a closed loop to stabilize the reading of the pressure sensor 17 at a slightly positive pressure of 2-5 kPa (relative to atmospheric pressure), and then synchronously starts the in-situ ultra-high temperature optical detection module 2 to zero-calibrate the signal baseline of all online detection instruments.

[0072] S2, Low-temperature organic matter analysis stage: First branch 311 is turned on, and second branch 312 and third branch 313 are turned off simultaneously. The micro fixed bed purification furnace 11 is controlled to heat from room temperature to 300°C at a first heating rate of 5°C / min, and the temperature is kept constant for 30min. The binder and residual electrolyte precipitated in the waste graphite material 111 to be tested enter the low-temperature organic matter detection unit 341 through the first branch 311 with the carrier gas for online component identification and tracking.

[0073] In the low-temperature organic matter desorption stage, the intelligent terminal issues a command to open the first valve 321 and close the second valve 322 and the third valve 323. The furnace heating layer 181 steadily heats up at a rate of 5℃ / min, reaching T1 (300℃) after time t1 (55 min), and is held at this temperature for t2 (30 min). It should be noted that the initial temperature can be room temperature. In this stage, 300℃ is selected as the first critical plateau because this temperature range can fully promote the thermal degradation and vaporization of organic binders (such as PVDF) and residual electrolyte on the surface of waste graphite, while lacking the thermodynamic energy to destroy impurities embedded in the crystal lattice, thereby achieving pure stripping of organic impurities. In addition, setting a slow heating rate of 5℃ / min can ensure that the gas phase mass transfer diffusion rate matches the retention and separation time of the downstream GC-MS column, avoiding excessively rapid heating that could lead to a concentrated burst of organic matter escaping and cause mass spectrometry signal overload. The binder, residual electrolyte, or adsorbed moisture on the surface of the waste graphite material 111 is vaporized by heating and enters the low-temperature organic matter detection unit 341 through the first branch 311, outputting the retention time and mass-to-charge ratio spectrum of organic impurities. During this stage, the first constant temperature heating layer 331 is maintained at 200-250℃, and the inert quartz liner 334 prevents the condensation and adsorption of large molecules.

[0074] S3, in the intermediate-temperature volatile impurity analysis stage, the intelligent terminal triggers a soft switching logic to open the second branch 312 and disconnect the first branch 311, controlling the micro fixed-bed purification furnace 11 to heat up to 1000℃ at a second heating rate of 5℃ / min, and maintain the temperature for 30min; the gaseous volatile metals escaping from the waste graphite material 111 to be tested enter the intermediate-temperature volatile impurity detection unit 342 for dynamic concentration monitoring;

[0075] During the intermediate-temperature volatile impurity analysis stage, after the low-temperature organic matter analysis is completed, the intelligent terminal initiates a soft switch, simultaneously and slowly opening the second valve 322 and closing the first valve 321. The furnace body of the micro fixed-bed purification furnace 11 continues to heat up to T2 (1000℃) at a rate of 5℃ / min for time t3 (140 min) and remains at that temperature for t4 (30 min). Setting 1000℃ as the second critical plateau is based on the fact that this temperature range just crosses the pyrolysis energy barrier of the inorganic salt layer (such as SEI film residue) on the surface of waste graphite, and is sufficient to cause alkali metal salt compounds (such as K2CO3, NaF, etc.) to undergo thermal decomposition and escape, and then be introduced into the intermediate-temperature volatile impurity detection unit 342 for real-time UV / Vis characteristic absorption peak analysis.

[0076] S4. During the high-temperature non-volatile impurity analysis stage, the soft switching logic is triggered to open the third branch 313 and simultaneously close the second branch 312. The heat tracing layer on the third branch 313 is started, and the micro fixed bed purification furnace 11 is controlled to heat up to the third set temperature range of 1800℃ at a third heating rate of 5℃ / min. During this stage, the in-situ ultra-high temperature optical detection module 2 continues to operate, and the non-volatile impurities that are vaporized and precipitated enter the high-temperature non-volatile substances and halides detection unit 343 for online measurement.

[0077] During the high-temperature non-volatile impurity analysis stage, the system performs a soft switch again, opening the third valve 323 and closing the second valve 322. The furnace body rises to T3 (1800℃) at a rate of 5℃ / min over time t5 (160min). 1800℃ is chosen as the third plateau segment because when the temperature exceeds this critical point, non-volatile metals and compounds (such as aluminum (A) and copper (Cu) deeply embedded within or between graphite sheets will break free of lattice constraints and escape. During this stage, the in-situ ultra-high temperature optical detection module 2 continues to operate, capturing the characteristic bright-line spectra emitted by the high-temperature volatilization of metal atoms in real time through the upper observation hole 14 within this temperature range. Meanwhile, to protect the extremely sensitive mass spectrometer at the back end, the online gas-liquid jet absorption interface 35 is activated, and ultrapure water or absorption liquid is pumped into the cold absorption liquid source 193 to instantly elute and quench the extremely high-temperature heavy metal sample gas into a liquid ion sample, which is then sent to the high-temperature non-volatile substances and halide detection unit 343 (ICP-MS) for online absolute quantification. The ultra-high temperature corrosion-resistant heat tracing layer 333 of the third branch circuit 313 is maintained at 300-600℃ throughout the process to prevent condensation.

[0078] S5. In the multi-field coupled halogenation purification stage, keep the third branch 313 open, and under isothermal conditions of 1800℃, cut into the micro fixed bed purification furnace 11 with halogen reaction gas, and maintain the reaction for 30 minutes; monitor the jump point and attenuation tail of the metal halide charge ratio signal in the high-temperature non-volatile substances and halide detection unit 343 in real time, and determine that the halogenation elution equilibrium reaction has been completed when the signal returns to the baseline.

[0079] In the multi-field coupled halogenation purification stage, during the isothermal plateau period of 1800℃, the second inlet 122 is controlled to cut into the halogen gas source 192, and the reaction is maintained for t6 (30 minutes). The halogen gas undergoes a high-temperature gas-solid halogenation reaction with the difficult-to-remove ultra-high temperature refractory metal impurities (such as titanium Ti, vanadium V, etc.). This ultra-high temperature environment provides a good thermodynamic driving force for the halogenation reaction, generating high vapor pressure metal halides, which are then eluted by the online gas-liquid jet absorption interface 35. During this process, the intelligent terminal receives the halide charge ratio (m / z) detection signal transmitted back in real time by the high-temperature non-volatile matter and halide detection unit 343 (i.e., ICP-MS equipment), and monitors the abrupt jump point and attenuation tail of the signal intensity in real time. When the signal returns to the baseline, it is determined that the halogenation elution equilibrium reaction has been completed. Subsequently, the halogen gas source 192 is cut off, and the pure argon gas purging and residue removal time t7 (30 minutes) is restored. The large amount of highly corrosive exhaust gas generated during this stage is effectively neutralized and absorbed by the exhaust gas treatment module 4.

[0080] S6. In the cooling and data fusion stage, the halogen reaction gas is cut off, and the system is naturally cooled to room temperature under the protection of inert carrier gas. The solid residue of the purified waste graphite material 111 to be tested is taken out, and its crystal interlayer spacing evolution and the residual amount of ultimate trace impurities are determined by the offline multi-scale characterization module 5. Finally, the intelligent terminal performs spatiotemporal correlation and alignment of the in-situ spectral data, online segmented detection data and offline characterization data, thereby effectively reconstructing the complete migration and transformation mechanism and evolution model map of various impurities in the waste graphite material 111 to be tested from "solid phase desorption and precipitation - gas phase transformation and migration - final solid phase residue".

[0081] Cooling, sampling, and evolution model construction were performed. The power supply to the furnace heating layer 181 and the halogen gas source 192 were shut off, maintaining only the continuous purging flow of high-purity argon gas in the gas inlet control unit 12. Utilizing the heat carried by the gas and the natural heat dissipation of the water-cooled jacket of the furnace protective layer 183, the system safely cooled to room temperature over time t8 (approximately 300 minutes). Subsequently, the purified high-purity graphite product was removed from the outlet 114 and sent to the offline multi-scale characterization module 5. Specifically, the removal of surface heterogeneous impurities and the microstructure were observed using the field emission scanning electron microscope 53; the interlayer spacing, crystallite size, and ID / IG ratio of graphite were calculated using the high-resolution X-ray diffractometer 52 and the confocal Raman spectrometer 51 to evaluate the repair of lattice defects and the improvement of graphitization degree; and the concentration of residual trace metal impurities was quantitatively determined using the inductively coupled plasma atomic emission spectrometer 54. Finally, the intelligent terminal performs time-stamp alignment and multi-dimensional fusion analysis on the "in-situ spectral thermal radiation spatiotemporal data" acquired in stages S2 to S5, the "online characteristic detection data of gas phase impurities" acquired by each high-temperature branch, and the "surface and interface morphology, crystal structure and trace residual background data" acquired by the above four devices in stage S6. This effectively reconstructs the complete migration and transformation mechanism and evolution model map of various impurities in the waste graphite material 111 to be tested, from "solid phase desorption and precipitation - gas phase transformation and migration - final solid phase residue".

[0082] Optionally, in steps S2-S5, the in-situ ultra-high temperature optical detection module 2 uses the lower observation hole 13 to collect the thermal radiation signal of the material bed surface to monitor the temperature fluctuation and physical state of the solid surface in real time, and uses the upper observation hole 14 to capture the characteristic bright line spectrum emitted when metal atoms volatilize and escape; the intelligent terminal timestamps the temperature time series data inverted by the lower observation hole 13 and the atomic emission characteristic peak data resolved by the upper observation hole 14, so as to realize the in-situ dynamic tracking of the migration and evolution process of impurities from solid to gas phase without destroying the gas dynamic flow field in the furnace.

[0083] Optionally, in steps S3 and S4, during pipeline switching, the intelligent terminal controls the valve to be opened to be in a gradual slow-opening state and the valve to be closed to be in a gradual slow-closing state. It also uses the pressure sensor 17 installed in the gas-thermal coupling high-temperature purification reaction module 1 to provide real-time feedback of the furnace pressure signal and dynamically adjust the opening compensation value of the two valves in a closed loop to maintain the gas pressure fluctuation amplitude inside the reaction zone to be less than ±0.5 kPa, ensuring a smooth transition between the carrier gas flow field and the spectral detection signal.

[0084] The core of this application's embodiment lies in deeply integrating the micro fixed-bed purification furnace 11 with a full-temperature-range segmented flow path, constructing a three-dimensional joint monitoring architecture with "in-situ—online—offline" capabilities. Through precise time-series segmentation across multiple temperature zones (room temperature - 300℃, 300-1000℃, 1000-1800℃ and above), the gaseous components escaping from the waste graphite material 111 at different thermodynamic critical points are directionally diverted to highly matched analytical instruments, effectively reducing cross-contamination and interference from the detection matrix among various complex evolutionary products in an ultra-wide temperature range. The beneficial effects of this application include at least:

[0085] (1) Staged detection: By setting up multi-branch flow paths and soft-switching valve timing control at the exhaust end of the gas-thermal coupling high-temperature purification reaction module 1, the targeted stripping detection of complex impurities was successfully realized. Organic impurities desorbed in the low-temperature zone (room temperature - 300℃), volatile alkali metals (such as K and Na) desorbed in the medium-temperature zone (300-1000℃), and refractory metals and halides that break through the crystal lattice bondage in the high-temperature zone (1000-1800℃) are each independently entered into the most suitable detection unit (GC-MS / UV-Vis / ICP-MS), which significantly improves the sensitivity and specificity of impurity detection in different temperature zones.

[0086] (2) Improved adaptability of high-temperature sample gas transmission: By setting an ultra-high temperature corrosion-resistant heat tracing layer 333 in the third branch 313, an online gas-liquid jet absorption interface 35 is innovatively introduced at the front end of mass spectrometry detection. Utilizing negative pressure shearing and instantaneous quenching of cold absorption liquid, the ultra-high temperature metal halide vapor containing strong corrosive substances is rapidly eluted and dissolved into a safe room-temperature liquid phase ion sample. This not only effectively inhibits the condensation and deposition of heavy metal vapor in the pipeline, but also significantly reduces the risk of serious damage to precision back-end detectors (such as ICP-MS) by corrosive gases.

[0087] (3) Possesses in-situ observation capability: By setting up upper and lower double observation holes at intervals along the flow field direction on the side wall of the purification furnace, and in conjunction with the ultra-high temperature resistant lens 151 and the multi-channel wide spectrum instrument 21, the thermal radiation temperature fluctuation of the solid bed surface and the impurity characteristic spectral signals of the gas phase above are respectively targeted and collected. In particular, the high-speed directional laminar flow protective gas curtain formed by the annular gas distribution ring 16 effectively blocks the condensation and fogging of high-temperature tar and metal vapor on the lens surface, and realizes in-situ high-fidelity dynamic monitoring of the migration and evolution of impurities from solid to gas phase without destroying the aerodynamic flow field inside the furnace.

[0088] (4) Reduce mutual interference between detection links: By arranging different types of detection units in parallel with relatively independent connections, the condensation and stacking of impurities and cross-contamination caused by the traditional single-channel sharing are avoided. In particular, in response to the problem of easy adsorption of organic impurities at low temperatures, an inert quartz liner 334 that has undergone chemical deactivation treatment is used to eliminate polar adsorption sites on the tube wall, significantly suppressing cross-interference and memory effect in cross-temperature zone detection, thereby ensuring the relative independence and high comparability of detection data in each temperature zone.

[0089] (5) Facilitates the construction of impurity evolution analysis process: Relying on intelligent terminals, high-frequency time-series data of non-contact in-situ spectroscopy, targeted concentration data of gas phase detection in each branch pipeline, and offline multi-scale residue characterization data (morphology, interlayer spacing, crystal defects, etc.) after cooling are aligned with high-precision timestamps. Through the fusion analysis of multivariate data, a panoramic impurity evolution law reconstruction system from micro-lattice precipitation, gas phase flow field migration to the final solid phase background residue is constructed, providing reliable data and model support for revealing the kinetic mechanism in the ultra-high temperature purification process.

[0090] (6) Providing a reference for purification process optimization: This invention, through precise diagnosis of the removal mechanism of specific impurities at specific temperatures, can guide the optimal parameter setting for industrial mass production. In particular, by demonstrating that introducing halogen gas source 192 at a specific time of 1800℃ to carry out gas-solid coupling replacement reaction can efficiently strip away high-temperature non-volatile impurities (such as titanium, vanadium, etc.), thus helping to replace the traditional pure pyrolysis process that requires pushing the furnace temperature to 2500℃ or even 3000℃ or higher. While ensuring the production of high-purity graphite, it provides technical support for the green recovery and ultra-high temperature purification of graphite anodes, significantly saving energy consumption and reducing equipment heat load, and has good industrial application and promotion value.

[0091] Example 2

[0092] like Figures 1 to 3As shown in the illustration, this application provides a detailed description of the gas-thermal coupling high-temperature purification reaction module 1, which includes: a micro fixed-bed purification furnace 11, a quick-release water-cooled flange 116, an air inlet control unit 12, an air distribution plate 124, and a loading crucible 112. The micro fixed-bed purification furnace 11 has a furnace cavity. The micro fixed-bed purification furnace 11 has a feed inlet 113, a discharge outlet 114, an air inlet, and an air outlet 123. The feed inlet 113, discharge outlet 114, air inlet, and air outlet 123 are all connected to the furnace cavity. The air inlet is located at the bottom of the micro fixed-bed purification furnace 11, and the air outlet 123 is located at the top of the micro fixed-bed purification furnace 11. The feed inlet 113 and discharge outlet 114 are located between the air inlet and the air outlet 123. A quick-release water-cooled flange 116 is detachably connected to the micro fixed-bed purification furnace 11 for closing or opening the feed inlet 113 and the discharge outlet 114. The air intake control unit 12 is connected to the air inlet. An air distribution plate 124 is located inside the furnace cavity and connected to the inner wall of the furnace cavity. The air distribution plate 124 is not higher than the feed inlet and discharge outlet, and has multiple air distribution holes. The air distribution plate 124 is located between the air inlet and the air outlet 123. The loading crucible 112 can be loaded into the furnace cavity through the feed inlet 113 and supported by the air distribution plate 124. The loading crucible 112 can be removed from the furnace cavity through the discharge outlet 114. In this application, by setting an air distribution plate 124 in the furnace cavity, it can both support the loading crucible 112 and disperse the gas evenly upward to form a stable inert protective atmosphere, so that the inert gas is evenly distributed, which is conducive to improving the purification effect and making the product quality meet expectations.

[0093] The furnace cavity volume of the micro fixed-bed purification furnace 11 can be flexibly designed between 50 mL and 2000 mL according to actual testing requirements. The micro fixed-bed purification furnace 11 is arranged from the inside out with a furnace body heating layer 181, a composite thermal insulation layer 182, and a furnace body protective layer 183 for providing a programmed heating thermal field. The furnace body heating layer 181 can use a high-purity graphite heating element or an induction heating coil to meet the ultra-wide temperature range heating requirements from room temperature to 3000℃, and the heating rate can be continuously adjusted between 1℃ / min and 50℃ / min. The composite thermal insulation layer 182 is preferably a multi-layer graphite felt structure for ultra-high temperature heat radiation shielding. The furnace body protective layer 183 can be a metal pressure-bearing shell with a water-cooled jacket.

[0094] The micro fixed-bed purification furnace 11 is equipped with a loading crucible 112 for carrying samples. To avoid background interference to the test results caused by the crucible material under ultra-high temperature or halogenated environments, the loading crucible 112 can be made of semiconductor-grade high-purity graphite or high-purity silicon carbide. Waste graphite material 111 can be filled into the loading crucible 112 in the form of powder or porous particles to form a material bed with uniform porosity distribution. The furnace body sidewall of the micro fixed-bed purification furnace 11 is respectively provided with a feed port 113 and a discharge port 114, and the feed port 113 and the discharge port 114 are preferably set at the same height. The discharge port end is equipped with a quick-release water-cooled flange 116 and a high-temperature resistant fluororubber sealing ring. The high-temperature resistant fluororubber sealing ring is used to seal the gap between the quick-release water-cooled flange 116 and the feed port 113 or discharge port 114.

[0095] In some possible implementations, the feed inlet 113 and the discharge outlet 114 are located at the same height and on opposite sides of the micro fixed-bed purification furnace 11. The air distribution plate 124 is located at the lower edge of the feed inlet 113 and the discharge outlet 114, facilitating the loading and unloading of the crucible 112. A horizontal guide rail 115 can be provided on the air distribution plate 124, with both ends of the horizontal guide rail 115 extending to the feed inlet 113 and the discharge outlet 114, respectively. The bottom of the loading crucible 112 has a sliding groove, and the loading crucible 112 slidably engages with the horizontal guide rail 115 through the sliding groove. The bottom of the furnace chamber of the micro fixed-bed purification furnace 11 is provided with a horizontal guide rail 115. The horizontal guide rail 115 is preferably a high-strength carbon-carbon composite material or high-purity graphite with a silicon carbide coating. The bottom groove of the loading crucible 112 slides in cooperation with the horizontal guide rail 115 to facilitate the loading and unloading of the loading crucible 112 by pushing and pulling it straight along the horizontal guide rail 115, thus avoiding the material spillage caused by the loading crucible 112 tilting or tilting.

[0096] Optionally, the distance between the air distribution plate and the air inlet is smaller than the distance between the air outlet 123 and the air distribution plate. That is, the air distribution plate 124 divides the furnace cavity into a bottom air distribution cavity and a top purification cavity. The space of the bottom air distribution cavity is smaller than that of the top purification cavity. On the one hand, this ensures that the top purification cavity has sufficient volume to completely accommodate the crucible; on the other hand, it allows the volume of the top purification cavity to be adapted to production requirements, ensuring uniform airflow distribution and stable temperature field within the furnace, and meeting the stability requirements of purification operation.

[0097] In some possible implementations, the air intake control unit 12 includes a three-way valve, an inert gas intake pipe, and a halogen gas intake pipe. The three-way valve has two inlets and one outlet, the outlet being connected to the air inlet, and the two inlets being connected to the inert gas intake pipe and the halogen gas intake pipe, respectively. The two inlets are a first inlet 121 and a second inlet 122. The first inlet 121 is connected to an external inert gas source 191 to provide system replacement, background maintenance, and carrier gas purging power. The second inlet 122 is connected to an external halogen gas source 192 to introduce reactive gas at a specific high-temperature stage to remove high-temperature non-volatile impurities (such as titanium, vanadium, etc.). After the gas enters the bottom air distribution chamber in the micro fixed-bed purification furnace 11, it is further sent to the top purification chamber through the air distribution plate 124.

[0098] In some possible implementations, a high-precision mass flow controller and an electronic fine-tuning valve can be configured on the pipeline of the intake control unit 12. For example, the high-precision mass flow controller and the electronic fine-tuning valve can be set on a three-way valve. The range of the high-precision mass flow controller can preferably be designed to be 0-1000 sccm. It should be noted that the key considerations for providing stable laminar flow power and maintaining a slightly positive pressure state of 2-5 kPa in this embodiment are: on the one hand, to ensure that the vaporized impurities escaping from the solid phase can be smoothly carried out by the carrier gas, avoiding the interference of the system background caused by external air leakage due to local negative pressure; on the other hand, to avoid the situation where the flow rate is too fast, resulting in insufficient spectral signal integration time during in-situ optical detection, or the situation where the flow rate is too slow, resulting in condensation and back mixing of gaseous heavy metal impurities in the pipeline. The specific implementation mainly describes the technical features that solve the impurity detection technology problem that this invention is actually intended to solve. The parts of the invention that overlap with the prior art, such as the gas cylinder pressure reducing valve and the safety explosion-proof membrane, are not described in detail, but this does not mean that the system technical solution in this invention is incomplete.

[0099] In some possible implementations, such as Figure 2 As shown, the micro fixed-bed purification furnace 11 is provided with a lower observation hole 13 and an upper observation hole 14. Both the lower observation hole 13 and the upper observation hole 14 are connected to the furnace cavity. The extension line of the lower observation hole 13 passes through the upper surface of the loading crucible 112, and the extension line of the upper observation hole 14 passes through the top area of ​​the loading crucible 112.

[0100] To enable in-situ observation of the gas-solid two-phase purification interface, the micro fixed-bed purification furnace 11 has a lower observation hole 13 and an upper observation hole 14 spaced apart on the same side wall along the upward flow direction of the carrier gas. In terms of spatial layout, the central axis of the lower observation hole 13 is directly aligned with the upper surface of the loading crucible 112, mainly used to collect the thermal radiation signal of the material bed to monitor the temperature fluctuation and physical state of the solid surface in real time; the central axis of the upper observation hole 14 is aligned with the gas phase escape region 10mm-50mm above the material bed, mainly used to capture the characteristic bright-line spectrum of impurity vapor during escape and diffusion.

[0101] In some possible implementations, such as Figure 2 As shown, the micro fixed-bed purification furnace 11 includes a main furnace body and two cylindrical shells. The main furnace body has the furnace cavity. Both cylindrical shells are horizontally arranged and connected to the main furnace body at one end. One cylindrical shell has the lower observation hole 13, and the other cylindrical shell has the upper observation hole 14. A high-temperature resistant lens and a dustproof glass lens 152 are arranged sequentially inside the cylindrical shells from the direction close to the main furnace body to the direction away from the main furnace body.

[0102] A high-temperature resistant lens 151 and a dustproof glass lens 152 are sequentially installed in the lower observation hole 13 and the upper observation hole 14 from the near end of the furnace cavity to the external cold end. The high-temperature resistant lens 151 is preferably made of sapphire glass with a wide spectrum of high light transmittance to isolate ultra-high temperature heat radiation; the dustproof glass lens 152 provides a secondary physical airtight seal.

[0103] In some possible implementation schemes, combined Figures 1 to 4 As shown, the gas-thermal coupling high-temperature purification reaction module 1 includes an annular gas distribution ring 16 and an inert gas source 191. The annular gas distribution ring 16 is disposed inside the shell and is located on the side of the ultra-high temperature lens away from the dustproof glass lens 152. The annular gas distribution ring 16 is provided with a plurality of micron-sized jet microholes, each of which is located on the side of the annular gas distribution ring 16 facing the furnace cavity. The annular gas distribution ring 16 is connected to the inert gas source 191.

[0104] To reduce the impact of high-temperature tar and metal vapor condensation and fogging on the lens surface, annular gas distribution rings 16 are provided on the side of the lower observation hole 13 and the upper observation hole 14 close to the inner surface of the ultra-high temperature resistant lens 151. The annular gas distribution ring 16 is connected to the inert gas source 191, and its inner ring is uniformly formed with multiple micron-sized jet micro-holes. During operation, high-pressure inert gas provided by the inert gas source 191 is ejected parallel from the jet micro-holes, adhering to and sweeping the inner surface of the ultra-high temperature resistant lens 151, forming a directional high-speed laminar flow gas curtain towards the center of the furnace. This effectively blocks the contact between the high-temperature vaporized impurities and the lens surface without interfering with the main airflow inside the furnace. Furthermore, the micro fixed-bed purification furnace 11 is also equipped with a highly sensitive pressure sensor 17, used to collect micro-pressure fluctuations inside the furnace cavity in real time at millisecond-level frequencies, providing feedforward control signals for downstream pipeline switching.

[0105] In some possible implementations, the feed inlet 113 and the discharge outlet 114 are located on both sides of the micro fixed-bed purification furnace 11 along a first direction, and the lower observation hole 13 and the upper observation hole 14 are located on one or both sides of the micro fixed-bed purification furnace 11 along a second direction, wherein the first direction and the second direction are perpendicular to each other. This avoids interference between the observation holes and the feed inlet 113 and the discharge outlet 114.

[0106] This application also provides a detection system and a graphite impurity detection system, which includes: the gas-thermal coupled high-temperature purification reaction module 1 and the in-situ ultra-high temperature optical detection module 2. The in-situ ultra-high temperature optical detection module 2 includes a multi-channel wide spectrometer 21 and a high-temperature resistant fiber array 22. One end of the high-temperature resistant fiber array 22 is connected to the multi-channel wide spectrometer 21, and the other end is connected to the observation hole on the micro fixed bed purification furnace 11.

[0107] The in-situ ultra-high temperature optical detection module 2 is arranged in a safe, room-temperature area outside the micro fixed-bed purification furnace 11, and includes a multi-channel broadband spectrometer 21. The multi-channel broadband spectrometer 21 is connected to the external optical paths of the lower observation aperture 13 and the upper observation aperture 14 via multiple high-temperature resistant fiber arrays 22. The detection wavelength range of the multi-channel broadband spectrometer 21 preferably covers 200 nm to 1100 nm, enabling real-time acquisition and analysis of the thermal radiation and atomic emission characteristic peaks of different metallic impurities under different temperature gradients, thereby achieving in-situ tracking of the impurity release process without disrupting the flow field.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A graphite impurity detection system, characterized in that, include: A gas-thermal coupling high-temperature purification reaction module includes a micro fixed-bed purification furnace. The micro fixed-bed purification furnace has a furnace cavity inside and is provided with an air inlet and an air outlet, both of which are connected to the furnace cavity. An intake control unit is connected to the air intake port; A full-temperature-range segmented online detection module is provided, wherein the input end of the full-temperature-range segmented online detection module is connected to the air outlet, and the full-temperature-range segmented online detection module includes a first branch, a second branch and a third branch. Valves and heat tracing layers are provided on the first branch, a low-temperature organic matter detection unit is provided on the first branch, a medium-temperature volatile impurity detection unit is provided on the second branch, and a high-temperature non-volatile matter and halogenation detection unit is provided on the third branch. The intelligent terminal is electrically connected to each of the valves to control the opening and closing of each valve.

2. The graphite impurity detection system according to claim 1, characterized in that, A Venturi tube section is installed on the third branch, and the Venturi tube section is located between the third valve and the high-temperature non-volatile substances and halides detection unit; An absorption port is provided at the narrowing section of the venturi tube, and the absorption port is connected to a cold absorption liquid source.

3. The graphite impurity detection system according to claim 1, characterized in that, Includes an exhaust gas treatment module; The ends of the first branch, the second branch, and the third branch are all connected to the exhaust gas treatment module; The exhaust gas treatment module includes a cryogenic trap, an alkaline gas scrubbing device, and a porous activated carbon adsorption device arranged in sequence.

4. The graphite impurity detection system according to claim 1, characterized in that, The low-temperature organic matter detection unit includes a gas chromatography-mass spectrometry system or a Fourier transform infrared spectrometer. The medium-temperature volatile impurity detection unit includes an ultraviolet-visible spectrometer, and the detection end of the ultraviolet-visible spectrometer is connected in series with an online gas flow cell with a heated quartz window. The high-temperature non-volatile and halide detection unit includes a liquid phase combined analysis system consisting of an ion chromatograph and an inductively coupled plasma mass spectrometer.

5. The graphite impurity detection system according to claim 1, characterized in that, It includes an offline multi-scale characterization module, which is used to evaluate the microstructure and quantitatively analyze trace impurities in the purified solid residue. The offline multi-scale characterization module includes at least one of a confocal Raman spectrometer, a high-resolution X-ray diffractometer, a field emission scanning electron microscope, and an inductively coupled plasma atomic emission spectrometer.

6. The graphite impurity detection system according to claim 1, characterized in that, It includes an in-situ ultra-high temperature optical detection module, which includes a multi-channel broadband spectrometer and a high-temperature resistant fiber array. One end of the high-temperature resistant fiber array is connected to the multi-channel broadband spectrometer, and the other end is connected to the observation port on the micro fixed bed purification furnace.

7. The graphite impurity detection system according to claim 6, characterized in that, The gas-thermal coupling high-temperature purification reaction module includes a loading crucible; The loading crucible can be accommodated within the furnace cavity; The micro fixed-bed purification furnace is provided with a lower observation hole and an upper observation hole, both of which are connected to the furnace cavity. The extension line of the lower observation hole passes through the upper surface of the loading crucible, and the extension line of the upper observation hole passes through the top area of ​​the loading crucible. The high-temperature resistant fiber array includes a first optical path and a second optical path, the first optical path extending to the lower observation aperture and the second optical path extending to the upper observation aperture.

8. The detection method of the graphite impurity detection system as described in any one of claims 1-7, characterized in that, The steps include the following: S1. Load the waste graphite material to be tested into the micro fixed bed purification furnace, introduce high-purity inert carrier gas at a preset flow rate through the air intake control unit, exhaust the air in the system, start the in-situ ultra-high temperature optical detection module, and initialize and calibrate the baseline of each detection instrument through the intelligent terminal. S2. In the low-temperature organic matter analysis stage, the first branch is turned on and the second and third branches are turned off simultaneously. The micro fixed bed purification furnace is controlled to heat from room temperature to 300°C at a first heating rate of 5°C / min and is kept at a constant temperature for 30min. The binder and residual electrolyte precipitated in the waste graphite material to be tested enter the low-temperature organic matter detection unit through the first branch with the carrier gas for online component identification and tracking. S3, in the intermediate-temperature volatile impurity analysis stage, the intelligent terminal triggers a soft switching logic to open the second branch and disconnect the first branch, controlling the micro fixed-bed purification furnace to heat to 1000℃ at a second heating rate of 5℃ / min, and maintain the temperature for 30min; the gaseous volatile metals escaping from the waste graphite material to be tested enter the intermediate-temperature volatile impurity detection unit for dynamic concentration monitoring. S4. During the high-temperature non-volatile impurity analysis stage, the soft switching logic is triggered to open the third branch and simultaneously close the second branch. The heat tracing layer on the third branch is activated, and the micro fixed bed purification furnace is controlled to heat up to the third set temperature range of 1800℃ at a third heating rate of 5℃ / min. During this stage, the in-situ ultra-high temperature optical detection module continues to operate, and the non-volatile impurities that are vaporized and precipitated enter the high-temperature non-volatile substances and halides detection unit for online measurement. S5. In the multi-field coupled halogenation purification stage, keep the third branch open and introduce halogen reaction gas into the micro fixed bed purification furnace under isothermal conditions of 1800℃. Maintain the reaction for 30 minutes. Monitor the jump point and attenuation tail of the metal halide charge ratio signal in the high-temperature non-volatile and halide detection unit in real time. When the signal returns to the baseline, it is determined that the halogenation elution equilibrium reaction has been completed. S6. In the cooling and data fusion stage, the halogen reaction gas is cut off, and the system is naturally cooled to room temperature under the protection of inert carrier gas. The solid residue of the purified waste graphite material to be tested is taken out, and its crystal interlayer spacing evolution and the residual amount of ultimate trace impurities are determined by the offline multi-scale characterization module. Finally, the intelligent terminal performs spatiotemporal correlation and alignment of the in-situ spectral data, online segmented detection data and offline characterization data, thereby effectively reconstructing the complete migration and transformation mechanism and evolution model map of various impurities in the waste graphite material to be tested from "solid phase desorption and precipitation - gas phase transformation and migration - final solid phase residue".

9. The detection method according to claim 8, characterized in that: In steps S2-S5, the in-situ ultra-high temperature optical detection module uses the lower observation hole to collect the thermal radiation signal of the material bed surface to monitor the temperature fluctuation and physical state of the solid surface in real time, and uses the upper observation hole to capture the characteristic bright line spectrum emitted when metal atoms volatilize and escape. The intelligent terminal timestamps the temperature time series data inverted by the lower observation hole and the atomic emission characteristic peak data resolved by the upper observation hole, so as to realize in-situ dynamic tracking of the migration and evolution process of impurities from solid to gas phase without disrupting the gas dynamic flow field inside the furnace.

10. The detection method according to claim 8, characterized in that: In steps S3 and S4, during pipeline switching, the intelligent terminal controls the valve to be opened to be in a gradual slow-opening state and the valve to be closed to be in a gradual slow-closing state. It also uses the pressure sensor installed in the gas-thermal coupling high-temperature purification reaction module to provide real-time feedback of the furnace pressure signal and dynamically adjust the opening compensation value of the two valves in a closed loop to maintain the gas pressure fluctuation amplitude inside the reaction zone to be less than ±0.5 kPa, ensuring a smooth transition between the carrier gas flow field and the spectral detection signal.

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