A continuous graphene preparation process based on argon arc rapid heating

Abstract

This invention discloses a continuous graphene preparation process based on rapid argon arc heating, belonging to the field of nanomaterial preparation technology. The process includes: Step S1: Raw material laying, where carbon-containing raw materials are uniformly laid in a tungsten-based ceramic square tank, controlling the raw material layer thickness to be 2–8 mm; Step S2: Atmosphere establishment, where an argon protection system is activated, and argon gas is introduced into the reaction zone at a flow rate controlled at 1–5 L / min to create an inert atmosphere; Step S3: Arc initiation and heating, where a voltage is applied between a tungsten electrode located above the raw materials and the bottom of the tungsten-based ceramic square tank using a DC power supply, breaking down the argon gas to form a stable electric arc. The current is adjusted to be greater than 150 A, causing the temperature in the reaction zone to rapidly rise to above 3000℃ within 50 ms. This invention avoids uneven product development caused by localized overheating or insufficient heating, ultimately obtaining high-quality graphene with fewer layers and lower defects. It is particularly suitable for the high-value, large-scale utilization of low-cost solid waste resources such as coal gangue and biomass.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, and in particular to a continuous graphene preparation process based on rapid argon arc heating. Background Technology

[0002] Graphene, as a two-dimensional carbon material with excellent photoelectric and thermal properties, has always been a research hotspot in terms of its large-scale preparation technology. Among existing rapid pyrolysis preparation technologies, flash Joule heating has attracted much attention due to its ability to achieve millisecond-level temperature rise. This technology utilizes high-current pulses to generate Joule heat through the raw materials, inducing carbon atom rearrangement to form graphene. However, this physical mechanism dictates that the raw materials must possess excellent electrical conductivity. For non-conductive or weakly conductive carbon-containing precursors such as coal gangue and biochar, existing technologies typically require the addition of conductive additives such as graphite felt and carbon black to construct a current path and ensure that the reaction zone reaches the required graphitization temperature (>2500℃). Although this heating mode, which relies on the conductivity of the raw materials, has been verified to be feasible in the laboratory stage, when dealing with solid waste raw materials with complex compositions, it is often necessary to precisely control the proportion of additives to balance conductivity and product purity.

[0003] While introducing conductive media has solved the heating problem of non-conductive raw materials, it has also introduced new process complexities. Because conductive additives are tightly mixed with the raw materials at high temperatures, subsequent separation and purification steps are significantly increased, not only driving up production costs but also easily leading to residual impurities and defects in the final graphene product, affecting the consistency of its intrinsic properties. Especially in high-end applications pursuing high-purity, low-layer graphene, the introduction of exogenous impurities has become a key factor restricting product quality improvement. Furthermore, traditional flash Joule heating often employs intermittent batch operations, making it difficult to achieve continuous and uniform feeding of raw materials and stable control of output, limiting its direct application in large-scale industrial production lines. Therefore, exploring a transient high-temperature preparation strategy that does not rely on the conductivity of the raw materials themselves, requires no auxiliary media, and can operate continuously is a pressing technical challenge in this field. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a continuous graphene preparation process based on argon arc rapid heating, which solves the problem that existing flash Joule heating technology must rely on conductive additives when processing non-conductive raw materials, resulting in limited product purity and difficulty in achieving continuous and stable production.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a continuous graphene preparation process based on argon arc rapid heating, which includes step S1: raw material laying, in which carbon-containing raw materials are evenly laid in a tungsten-based ceramic square groove, and the thickness of the raw material layer is controlled to be 2–8 mm. Step S2: Atmosphere setup: Start the argon protection system and introduce argon into the reaction zone at a flow rate of 1–5 L / min to create an inert atmosphere. Step S3: Arc ignition heating. Apply voltage between the tungsten electrode located above the raw material and the bottom of the tungsten ceramic square tank using a DC power supply to break down the argon gas and form a stable electric arc. Adjust the current to be greater than 150 A so that the temperature of the reaction zone can be rapidly raised to above 3000℃ within 50 ms. Step S4: Continuous movement, the slide rail system driven by the CNC stepper motor drives the tungsten-based ceramic square tank containing the raw material to pass through the electric arc heating zone at a speed of 5–20 mm / s, so that the raw material completes the instantaneous high-temperature graphitization reaction during the movement. Step S5: Cooling and collection. The reacted material is moved out of the heating zone by the slide rail and cooled to room temperature under argon protection. The generated graphene product is then collected.

[0007] As a preferred embodiment of the continuous graphene preparation process based on argon arc rapid heating described in this invention, the carbon-containing raw material in step S1 is selected from one or more of high-purity graphite powder, coal gangue, biochar, wood chips, straw, or garden waste. When the carbon-containing raw material is a non-conductive or weakly conductive material (coal gangue, biochar, wood chips, straw, or garden waste), it can be laid directly without adding graphite paper, graphite felt, or other auxiliary conductive materials.

[0008] Furthermore, the carbon-containing raw materials in step S1 have broad applicability, not only covering traditional high-purity graphite powder, but also extending to low-cost non-conductive or weakly conductive biomass and solid waste materials such as coal gangue, biochar, wood chips, straw, and garden waste. The core advantage of this solution is that it completely eliminates the cumbersome process of adding auxiliary conductive media such as graphite paper, graphite felt, or metal powder to solve the heating problem of non-conductive raw materials in the existing technology. It allows the above-mentioned raw materials to be directly and uniformly laid in the reaction tank, avoiding the introduction of exogenous impurities from the source, reducing the cost of raw material pretreatment and improving the intrinsic purity of the final graphene product.

[0009] As a preferred embodiment of the continuous graphene preparation process based on argon arc rapid heating described in this invention, wherein: the tungsten-bottom ceramic square groove in step S1 is composed of a high-temperature resistant ceramic groove and a tungsten electrode plate embedded in the bottom of the groove; The tungsten plate is connected to the DC power supply as the positive electrode, and the tungsten electrode is connected to the DC power supply as the negative electrode. The effective working width of the tungsten-based ceramic square groove is 5-15 mm, the height is 6-20 mm, and the length is set according to production needs but not less than 10 mm.

[0010] Furthermore, the tungsten-bottomed ceramic square tank used in step S1 is a composite structure reaction vessel specifically designed for high-temperature electric arc environments. It is composed of a special ceramic tank body that is resistant to high temperatures and thermal shock and a tungsten electrode plate that is precisely embedded in the bottom of the tank body. In terms of electrical connection, the bottom tungsten electrode plate is connected to the DC power supply as the positive electrode, and together with the negative tungsten electrode suspended above, they form a stable discharge circuit. The geometric dimensions of the vessel are optimized, with the effective working width controlled at 5-15 mm to match the arc focusing range, the height set at 6-20 mm to accommodate raw material layers of different thicknesses, and the length flexibly set according to the layout requirements of the continuous production line and not less than 10 mm, ensuring the uniformity of the thermal field and the structural stability of the reaction zone.

[0011] As a preferred embodiment of the continuous graphene preparation process based on rapid argon arc heating described in this invention, in step S3, an infrared thermometer is used to monitor the temperature of the reaction zone in real time without contact, and the temperature signal is fed back to the power control system. When the monitored temperature is below 3000℃, the output current is automatically increased or the slide rail movement speed is reduced; when the monitored temperature is above the set threshold, the output current is automatically reduced or the slide rail movement speed is increased to maintain the reaction zone temperature stable in the range of 3000℃-3500℃.

[0012] Furthermore, step S3 introduces a high-precision closed-loop temperature control strategy. A non-contact infrared thermometer is used to monitor the arc reaction zone in real time at the millisecond level, and the collected temperature signal is fed back to the intelligent power control system in real time. The system has a built-in dynamic adjustment algorithm. When the temperature of the reaction zone is detected to be below the graphitization critical value of 3000℃, the system automatically commands to increase the output current or reduce the sliding rail movement speed to increase the heating energy per unit mass of raw material. Conversely, when the temperature exceeds the safety threshold, the system automatically reduces the current or increases the movement speed, thereby accurately locking the reaction temperature in the optimal graphitization range of 3000℃-3500℃, effectively avoiding product defects or equipment damage caused by temperature fluctuations.

[0013] As a preferred embodiment of the continuous graphene preparation process based on rapid argon arc heating described in this invention, wherein: the argon gas purity in step S2 is greater than 99.6%, and the argon gas is confined to the arc reaction area by a ceramic sealed argon gas flow device; If the argon flow rate is less than 1 L / min, it will lead to difficulty in arc initiation and an increase in product oxidation defects; if the argon flow rate is greater than 5 L / min, it will lead to unstable arc disturbance and material scattering.

[0014] Furthermore, step S2 strictly defines the quality and flow field of the protective atmosphere, requiring that the purity of the argon gas used must be greater than 99.6%, and that the inert gas is precisely confined to the core area of ​​the arc reaction through a specially designed ceramic sealed argon gas flow device to form a local high-purity protective environment. This scheme clarifies the critical window of argon gas flow rate. If the flow rate is less than 1 L / min, it is insufficient to completely displace the air, which will lead to difficulties in arc initiation and defects in the oxidation of carbon atoms at high temperatures. If the flow rate is greater than 5 L / min, the excessively strong high-speed gas flow will disturb the stability of the arc plasma and cause light raw materials to scatter. Therefore, the flow rate control of 1–5 L / min is a key parameter for balancing the anti-oxidation effect and the arc stability.

[0015] In a preferred embodiment of the continuous graphene preparation process based on rapid argon arc heating described in this invention, in step S4, the sliding rail moving speed is dynamically adjusted according to the raw material layer thickness and current magnitude. When the thickness of the raw material layer is close to 8 mm, the sliding rail moving speed is set to 5-10 mm / s to ensure that the lower layer of raw material is fully heated. When the thickness of the raw material layer is close to 2 mm, the slide rail moving speed is set to 15-20 mm / s to improve production efficiency and prevent overheating and erosion.

[0016] Furthermore, step S4 establishes a dynamic coupling mechanism between the slide rail moving speed, the raw material layer thickness, and the heating power, enabling adaptive adjustment of process parameters. For thicker raw material layers (approximately 8 mm), the system reduces the moving speed to 5-10 mm / s to extend the high-temperature residence time, ensuring that heat fully penetrates to the bottom raw material to complete graphitization. For thinner raw material layers (approximately 2 mm), the speed is increased to 15-20 mm / s, significantly improving the output efficiency per unit time while ensuring sufficient reaction and preventing carbon material ablation due to overheating, thus achieving an optimal balance between production efficiency and product quality.

[0017] As a preferred embodiment of the continuous graphene preparation process based on argon arc rapid heating described in this invention, the graphene product obtained by the process is characterized by Raman spectroscopy. A ratio greater than or equal to 1.5 indicates that the product mainly consists of a 1-2 layer graphene structure. That The ratio is approximately 0.58, indicating that the product has high crystallinity and few defects.

[0018] Furthermore, the graphene products prepared by this process exhibit superior quality characteristics in their microstructure. Fine Raman spectroscopy characterization shows that the ratio of its 2D peak to G peak is consistently greater than or equal to 1.5. This indicator confirms that the product is mainly composed of high-quality 1-2 layers of few-layer graphene, possessing excellent electrical transport potential. Simultaneously, the ratio of its D peak to G peak is controlled at a low level of approximately 0.58, indicating that during the instantaneous ultra-high temperature rapid cooling process, the carbon lattice rearrangement is complete, with very few internal structural defects and extremely high crystallinity, meeting the stringent performance requirements of graphene materials for high-end electronic devices and composite materials.

[0019] As a preferred embodiment of the continuous graphene preparation process based on argon arc rapid heating described in this invention, the process supports a multi-tank parallel continuous production mode, including multiple tungsten-based ceramic square tanks arranged in parallel and corresponding multiple sets of tungsten electrodes; Each set of tungsten-based ceramic square tanks is independently driven by a CNC stepper motor, and different moving speeds and heating powers can be set to adapt to the synchronous processing of different types of carbon-containing raw materials.

[0020] Furthermore, this process possesses high scalability and flexible production capabilities, supporting a continuous production mode with multiple tanks in parallel. This involves setting up multiple independent tungsten-based ceramic square tanks and corresponding tungsten electrode arrays in parallel within the production line. Each production unit is equipped with an independent CNC stepper motor drive system, allowing operators to set differentiated moving speed and heating power parameters based on the physicochemical properties (such as thermal conductivity and volatile matter content) of different batches of carbon-containing raw materials. This enables simultaneous and differentiated processing of various types of raw materials, significantly improving the overall capacity of the production line and its responsiveness to market demands.

[0021] As a preferred embodiment of the continuous graphene preparation process based on rapid argon arc heating described in this invention, the DC power supply system parameters in step S3 are: adjustable current 0-500 A and adjustable voltage 0-320 V. At the moment of arc initiation, the power supply uses a high-frequency, high-voltage pulse to break down the argon gas, and then switches to a high-current DC mode to maintain stable arc combustion.

[0022] Furthermore, the DC power supply system used in step S3 has wide-range adjustability and special arc ignition control logic. Its output current can be steplessly adjusted within the range of 0-500 A, and its voltage can be precisely controlled within the range of 0-320 V. During the process start-up stage, the power supply first outputs a high-frequency high-voltage pulse signal to instantly break down the argon medium and establish an initial conductive channel. Then, it seamlessly switches to a high-current DC mode to maintain stable arc combustion and continuous high-heat output. This dual-mode control strategy of "pulse arc ignition + DC arc stabilization" effectively ensures the success rate and stability of the arc in the non-contact arc ignition process.

[0023] As a preferred embodiment of the continuous graphene preparation process based on argon arc rapid heating described in this invention, the process further includes failure boundary control logic: If the slide rail stops moving, immediately cut off the power to prevent localized burning. If an interruption or insufficient pressure of argon gas is detected, immediately cut off the power and sound an alarm to prevent oxygen from the air from entering and causing product oxidation. If the detected current is below 150 A, the system will be prohibited from starting or will automatically shut down to ensure that no low-quality products are produced when the instantaneous high temperature of 3000℃ cannot be reached.

[0024] Furthermore, the process integrates multiple failure boundary intelligent control logics to ensure production safety and product consistency. The system monitors key operating parameters in real time and executes interlock protection. Once an unexpected stop of the slide rail is detected, the power is immediately cut off to prevent local overheating and ablation of the equipment. If an interruption in argon supply or insufficient pressure is detected, the power is immediately cut off and an audible and visual alarm is triggered to prevent high-temperature oxidation accidents caused by air ingress. If the operating current is detected to be below the critical value of 150 A, the system will prohibit startup or automatically shut down to ensure that low-quality intermediate products are not produced when the instantaneous high temperature condition of 3000℃ is not met, thus guaranteeing the uniformity of product quality from a mechanism perspective.

[0025] The beneficial effects of this invention are as follows: By directly laying non-conductive carbon-containing raw materials on a specially made tungsten-based ceramic square groove and combining it with argon gas local confinement protection, it is possible to achieve instantaneous ultra-high temperature heating of the raw materials using an external independent argon arc heat source without adding any auxiliary conductive medium. This fundamentally solves the problem of introducing impurities and defects due to the reliance on the conductivity of the raw materials in the traditional Joule heating method, significantly improving the intrinsic purity and crystal quality of the graphene product. At the same time, by driving the raw materials to continuously and uniformly pass through the high-temperature arc zone using a CNC slide rail and coupling infrared temperature measurement feedback to dynamically adjust the process parameters, the graphitization reaction is transformed from intermittent batch operation to efficient continuous production. This ensures that raw material layers of different thicknesses can obtain a uniform and suitable thermal history, which not only greatly improves production efficiency and capacity stability, but also effectively avoids product unevenness caused by local overheating and ablation or insufficient heating. Ultimately, high-quality graphene with fewer layers and fewer defects is obtained, which is particularly suitable for the high-value large-scale utilization of low-cost solid waste resources such as coal gangue and biomass. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a flow chart of a continuous argon arc rapid high-temperature process.

[0028] Figure 2 This is a schematic diagram of a continuous argon arc rapid high-temperature device.

[0029] Figure 3 This is a schematic diagram of the Raman spectrum of graphene formed by a continuous argon arc rapid high-temperature process.

[0030] Figure 4 A schematic diagram of the TEM sheet structure of graphene formed by a continuous argon arc rapid high-temperature process.

[0031] Figure 5 This is a schematic diagram showing the relationship between temperature and time under different currents.

[0032] Figure 6 This is a schematic diagram of the Raman spectrum of a case where low current was not successfully applied.

[0033] Figure 7 This diagram illustrates the effect of the thickness of the graphene layer on the quality of the graphene.

[0034] Figure 8 This diagram illustrates the impact of the laying thickness on the success rate of arc initiation.

[0035] Figure 9 This is a flowchart illustrating the effect of slide rail speed on graphene quality.

[0036] Figure 10 This diagram illustrates the impact of quantity on graphene quality and graphene yield.

[0037] Figure 11 A schematic diagram of the quality of graphene obtained by partitioning the product obtained from the heating process.

[0038] Figure 12 A schematic diagram showing the quality of graphene prepared under different currents to set up argon gas sealing protection.

[0039] Figure 13 This diagram illustrates that the quality of graphene remained unchanged within 4 hours of continuous production. Detailed Implementation

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0043] Reference Figures 1-13 This is one embodiment of the present invention, which provides a continuous graphene preparation process based on argon arc rapid heating, including the following steps: 1. Raw material preparation and laying (step S1) Dried wood chips were selected as the carbon-containing raw material, crushed, and sieved to obtain wood chip powder with uniform particle size. The wood chip powder was then evenly spread in a specially made tungsten-based ceramic square trough, with the thickness of the raw material layer controlled at 4 mm.

[0044] Device Details: The tungsten-bottomed ceramic square channel consists of a high-temperature resistant ceramic tank and a tungsten electrode plate embedded in the bottom, with an effective working width of 10 mm and a height of 12 mm. Wood chips, as a non-conductive material, are laid directly without the need for any conductive auxiliary media such as graphite felt or carbon black.

[0045] 2. Atmosphere creation (step S2) The argon protection system is activated, and 99.9% pure argon gas is introduced into the reaction zone through a ceramic-sealed argon gas flow device at a flow rate of 3 L / min to create a stable local inert atmosphere and prevent the carbon raw materials from oxidizing at high temperatures.

[0046] 3. Arc initiation heating and temperature control (step S3) The DC power supply system was started, and a voltage was applied between the tungsten electrode (negative electrode) located 2 mm above the raw material and the tungsten electrode plate (positive electrode) at the bottom of the tank. The power supply first output a high-frequency, high-voltage pulse to break down the argon gas, and then switched to a high-current DC mode, adjusting the current to 200 A. The electric arc rapidly raised the temperature of the reaction zone to 3200 °C within 50 ms.

[0047] Feedback adjustment: The system uses an infrared thermometer to monitor the temperature in real time. When the detected temperature fluctuation is below 3000℃, the system automatically adjusts and increases the current; when it is above 3500℃, the system automatically decreases the current to ensure that the temperature is stable in the range of 3000℃-3500℃.

[0048] 4. Continuous movement and graphitization (step S4) The CNC stepper motor drives the slide rail system, which in turn moves the tungsten-based ceramic square groove containing wood chips through the arc heating zone at a constant speed of 12 mm / s. Due to the moderate layup thickness (4 mm), this speed ensures that the wood chips complete the devolatileization and graphitization rearrangement at instantaneous high temperature, while avoiding overheating and ablation.

[0049] 5. Cooling and Collection (Step S5) The reacted material was moved out of the heating zone by a slide rail and naturally cooled to room temperature under continuous argon protection. The resulting black, fluffy product was collected and preliminarily screened to obtain graphene powder.

[0050] 6. Product Characterization Raman spectroscopy of the product showed that... I 2D / I G The ratio of 1.6 indicates that the product mainly consists of a 1-2 layer graphene structure. I D / I G A ratio of 0.55 indicates high crystallinity and few defects. This embodiment successfully achieved the conversion of non-conductive biomass into high-quality graphene without the need for conductive additives.

[0051] Example 2: Preparation based on dynamic parameter optimization of thick coal gangue solid waste raw materials 1. Raw material preparation and laying (step S1) Pretreated coal gangue powder was selected as the carbon-containing raw material (weakly conductive material). To test the process's adaptability to thick material layers, the coal gangue powder was tightly and evenly spread in a tungsten-based ceramic square channel, with the raw material layer thickness controlled at 8 mm (close to the upper limit). No auxiliary conductive material was required.

[0052] 2. Atmosphere creation (step S2) Argon gas with a purity greater than 99.6% is introduced, and the flow rate is strictly controlled at 4.5 L / min. A higher flow rate helps to remove the large amount of volatile gases produced by the high-temperature decomposition of coal gangue, maintaining the purity of the reaction zone.

[0053] 3. Arc initiation heating (step S3) Adjust the DC power supply output current to 280 A, and use high-frequency pulses to break down the argon gas and maintain a large current discharge, so that the temperature of the reaction zone rises to 3300℃ in a very short time.

[0054] 4. Dynamic speed adjustment (Step S4—Core innovation) Given that the raw material layer thickness reaches 8 mm, in order to ensure that the lower layer of raw material can also be fully heated to complete graphitization, the system automatically reduces the sliding rail movement speed to 6 mm / s according to the preset logic.

[0055] Effect analysis: The slower moving speed prolongs the residence time of the thick material in the high-temperature zone, solves the problem of uneven heat transfer in the thick material layer, and avoids the phenomenon of "graphitization on the surface and unreacted inside".

[0056] 5. Security monitoring and failover protection (step S10) During operation, the system monitors the slide rail status and current value in real time. If the current is detected to drop to 140 A (below the critical value of 150 A) due to load fluctuations at a certain moment, the system will immediately trigger automatic shutdown protection to prevent the generation of low-quality semi-graphitized products, and will restart after the fault is cleared.

[0057] 6. Cooling, Collection, and Results The material was removed, cooled, and collected. Raman spectroscopy showed that even for an 8 mm thick layer of coal gangue feedstock, the product... I 2D / I G I 2D / I G The ratio still reached 1.52. I G / I G I D / I G The ratio is 0.59. This demonstrates that by dynamically adjusting the moving speed, this process can effectively process complex solid waste materials of varying thicknesses, and the product quality is uniform.

[0058] Example 3: Synchronous and continuous production of multiple raw materials in a multi-tank parallel mode 1. System Configuration (Step S8) A multi-slot parallel continuous production line was built, with three parallel tungsten-based ceramic square slots (slot A, slot B, and slot C). Each slot corresponds to an independent set of tungsten electrodes and a CNC stepper motor drive system.

[0059] Tank A: Loaded with 2 mm thick high-purity graphite powder.

[0060] Tank B: Loaded with 5 mm thick biochar.

[0061] Tank C: Loaded with 8 mm thick straw powder.

[0062] 2. Setting Differentiation Parameters (Steps S4 & S6) Start the system and set independent operating parameters for each of the three different raw materials, taking into account their characteristics: Tank A (thin-layer high-purity graphite): The slide rail movement speed is set to 18 mm / s, and the current is 160 A. High-speed operation is used to improve production efficiency and prevent excessive ablation of the high-purity graphite.

[0063] Tank B (middle layer biochar): Set the slide rail movement speed to 10 mm / s and the current to 220 A. Balance heating efficiency and output.

[0064] Groove C (thick layer of straw): Set the slide rail movement speed to 5 mm / s and the current to 300 A. Low speed ensures complete graphitization of the thick layer of straw.

[0065] 3. Uniform atmosphere and independent heating (steps S2 and S3) The entire production line shares an argon gas protection system, but the gas flow is confined to the reaction zone of each tank through sealing devices. The three power supplies operate independently, all using a "high-frequency pulse breakdown + DC arc stabilization" mode, without interfering with each other.

[0066] 4. Continuous production and collection (step S5) The raw materials in the three tanks are simultaneously passed through their respective electric arc heating zones, undergoing an instantaneous high-temperature reaction before being removed and cooled. The three discharge ports collect graphene products from three different raw material sources.

[0067] 5. Overall Effect This embodiment demonstrates the industrialization potential of the process. Through parallel connection of multiple slots and independent control, the following was achieved: Flexible production: The same production line can process different types and thicknesses of raw materials at the same time without stopping the machine to change materials or readjust the parameters of the entire line.

[0068] Efficiency improvement: Compared to single-tank intermittent operation, the production capacity is increased several times.

[0069] Quality stability: Products from each channel were tested. I 2D / I G I 2D / I G The ratios are all greater than 1.5. I D / I G I D / I G The ratios are all around 0.6, proving that under multi-channel parallel operation, the temperature field and atmosphere field of each reaction zone remain highly stable and independently controllable.

[0070] In summary, this invention achieves instantaneous ultra-high temperature heating of the raw material using an external independent argon arc heat source without the need for any auxiliary conductive medium by directly laying non-conductive carbon-containing raw materials on a specially designed tungsten-based ceramic square groove and combining it with localized argon gas confinement protection. This fundamentally solves the problem of introducing impurities and defects due to reliance on the conductivity of the raw material in the traditional Joule heating method, significantly improving the intrinsic purity and crystal quality of the graphene product. Simultaneously, by driving the raw material through the high-temperature arc zone continuously and uniformly using a CNC sliding rail and coupling infrared temperature feedback to dynamically adjust process parameters, the graphitization reaction is transformed from intermittent batch operation to efficient continuous production. This ensures that raw material layers of different thicknesses can obtain a uniform and suitable thermal history, which not only greatly improves production efficiency and capacity stability but also effectively avoids product unevenness caused by localized overheating or underheating. Ultimately, it yields high-quality graphene with fewer layers and fewer defects, making it particularly suitable for the high-value-added large-scale utilization of low-cost solid waste resources such as coal gangue and biomass.

[0071] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A continuous graphene preparation process based on argon arc rapid heating, characterized in that: include, Step S1: Raw material laying. The carbon-containing raw material is evenly laid in the tungsten-based ceramic square groove, and the thickness of the raw material layer is controlled to be 2–8 mm. Step S2: Atmosphere setup: Start the argon protection system and introduce argon into the reaction zone at a flow rate of 1–5 L / min to create an inert atmosphere. Step S3: Arc ignition heating. Apply voltage between the tungsten electrode located above the raw material and the bottom of the tungsten ceramic square tank using a DC power supply to break down the argon gas and form a stable electric arc. Adjust the current to be greater than 150 A so that the temperature of the reaction zone can be rapidly raised to above 3000℃ within 50 ms. Step S4: Continuous movement, the slide rail system driven by the CNC stepper motor drives the tungsten-based ceramic square tank containing the raw material to pass through the electric arc heating zone at a speed of 5–20 mm / s, so that the raw material completes the instantaneous high-temperature graphitization reaction during the movement. Step S5: Cooling and collection. The reacted material is moved out of the heating zone by the slide rail and cooled to room temperature under argon protection. The generated graphene product is then collected.

2. The continuous graphene preparation process based on argon arc rapid heating as described in claim 1, characterized in that: The carbon-containing raw material in step S1 is selected from one or more of high-purity graphite powder, coal gangue, biochar, wood chips, straw, or garden waste. When the carbon-containing raw material is a non-conductive or weakly conductive material (coal gangue, biochar, wood chips, straw, or garden waste), it can be laid directly without adding graphite paper, graphite felt, or other auxiliary conductive materials.

3. The continuous graphene preparation process based on argon arc rapid heating as described in claim 2, characterized in that: The tungsten-bottom ceramic square groove in step S1 is composed of a high-temperature resistant ceramic tank and a tungsten electrode plate embedded in the bottom of the tank. The tungsten plate is connected to the DC power supply as the positive electrode, and the tungsten electrode is connected to the DC power supply as the negative electrode. The effective working width of the tungsten-based ceramic square groove is 5-15 mm, the height is 6-20 mm, and the length is set according to production needs but not less than 10 mm.

4. The continuous graphene preparation process based on argon arc rapid heating as described in claim 3, characterized in that: In step S3, an infrared thermometer is used to monitor the temperature of the reaction zone in real time without contact, and the temperature signal is fed back to the power control system. When the monitored temperature is below 3000℃, the output current is automatically increased or the slide rail movement speed is reduced; when the monitored temperature is above the set threshold, the output current is automatically reduced or the slide rail movement speed is increased to maintain the reaction zone temperature stable in the range of 3000℃-3500℃.

5. The continuous graphene preparation process based on argon arc rapid heating as described in claim 4, characterized in that: In step S2, the argon gas has a purity greater than 99.6%, and the argon gas is confined to the arc reaction area by a ceramic-sealed argon gas flow device. If the argon flow rate is less than 1 L / min, it will lead to difficulty in arc initiation and an increase in product oxidation defects; if the argon flow rate is greater than 5 L / min, it will lead to unstable arc disturbance and material scattering.

6. The continuous graphene preparation process based on argon arc rapid heating as described in claim 5, characterized in that: In step S4, the sliding rail moving speed is dynamically adjusted based on the raw material layer thickness and current magnitude. When the thickness of the raw material layer is close to 8 mm, the sliding rail moving speed is set to 5-10 mm / s to ensure that the lower layer of raw material is fully heated. When the thickness of the raw material layer is close to 2 mm, the slide rail moving speed is set to 15-20 mm / s to improve production efficiency and prevent overheating and erosion.

7. The continuous graphene preparation process based on argon arc rapid heating as described in claim 6, characterized in that: The graphene product obtained by the process was characterized by Raman spectroscopy. A ratio greater than or equal to 1.5 indicates that the product mainly consists of a 1-2 layer graphene structure. That The ratio is approximately 0.58, indicating that the product has high crystallinity and few defects.

8. The continuous graphene preparation process based on argon arc rapid heating as described in claim 7, characterized in that: The process supports a multi-slot parallel continuous production mode, including multiple tungsten-based ceramic square slots arranged in parallel and corresponding multiple sets of tungsten electrodes; Each set of tungsten-based ceramic square tanks is independently driven by a CNC stepper motor, and different moving speeds and heating powers can be set to adapt to the synchronous processing of different types of carbon-containing raw materials.

9. The continuous graphene preparation process based on argon arc rapid heating as described in claim 8, characterized in that: The DC power supply system parameters in step S3 are: adjustable current 0-500 A and adjustable voltage 0-320 V. At the moment of arc initiation, the power supply uses a high-frequency, high-voltage pulse to break down the argon gas, and then switches to a high-current DC mode to maintain stable arc combustion.

10. The continuous graphene preparation process based on argon arc rapid heating as described in claim 9, characterized in that: The process also includes failure boundary control logic: If the slide rail stops moving, immediately cut off the power to prevent localized burning. If an interruption or insufficient pressure of argon gas is detected, immediately cut off the power and sound an alarm to prevent oxygen from the air from entering and causing product oxidation. If the detected current is below 150 A, the system will be prohibited from starting or will automatically shut down to ensure that no low-quality products are produced when the instantaneous high temperature of 3000℃ cannot be reached.

Images