A method for producing high quality graphite using forestry waste and the resulting graphite

Abstract

The application discloses a method for preparing high-quality graphite by using forestry wastes and the obtained graphite, and belongs to the technical field of carbon material preparation. The method comprises the following steps: drying forestry wastes, crushing and pretreating the dried forestry wastes, mixing the pretreated forestry wastes with a solid oxidizing agent, and then activating the mixture in an inert gas atmosphere at 400-600 DEG C; carbonizing the activated sample in an inert gas atmosphere at 800-1000 DEG C; mixing the carbonized sample with a high-temperature graphitization catalyst after water washing and drying, and then performing high-temperature graphitization treatment on the mixture at 2500-3000 DEG C; and sequentially performing water washing, screening, acid solution immersion, water washing, drying and ball milling on the sample after the high-temperature graphitization treatment, so that the high-quality graphite is obtained. The method can fully utilize forestry waste resources and obtain high-quality graphite, and the high-quality graphite has high purity, high thermal conductivity and electrical conductivity, and is suitable for sealing materials.

Description

Technical Field

[0001] This invention relates to the field of carbon material preparation technology, and in particular to a method for preparing high-quality graphite using forestry waste and the resulting graphite. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Graphite possesses unique physical and chemical properties that make it an excellent sealing material. Firstly, graphite exhibits outstanding high-temperature stability, maintaining its stable performance even at extreme temperatures. This allows it to retain elasticity and a stable sealing effect in high-temperature environments, without easily softening or melting. Secondly, graphite is resistant to corrosion from many chemicals, resisting the erosion of acids, alkalis, and other substances while maintaining its stability. This enables graphite to provide reliable sealing effects in various chemical environments. Furthermore, sealing materials made from graphite also possess good compressibility and elasticity, allowing them to adapt to joints of different shapes, fill gaps, and provide excellent sealing performance. Graphite used for sealing materials usually also needs to have the following properties: (1) High purity requirement: Graphite used in sealing applications usually requires high purity to reduce the impact of impurities on sealing performance; low impurity content helps ensure that graphite materials do not produce additional corrosion, oxidation or chemical reactions during the sealing process, and maintain their stability; generally, the purity of graphite materials is required to be as high as 95-99% or more; (2) Thermal conductivity requirement: Graphite sealing materials usually need to have excellent thermal conductivity, which can quickly transfer and disperse heat, help maintain a stable temperature of the sealing environment, and reduce leakage caused by thermal expansion and contraction; the thermal conductivity coefficient of graphite sealing materials is in the range of 150W / mK to 500W / mK; (3) Electrical conductivity requirement: Some special sealing scenarios may require graphite to have good electrical conductivity in order to achieve electromagnetic shielding or electrical conductivity sealing functions; it is usually required to be in the range of 50000S / m to 500000S / m to achieve good electrical conductivity performance.

[0004] The supply gap for natural graphite is widening. Currently, artificial graphite is mainly produced from high-carbon materials such as petroleum coke, pitch coke, anthracite, graphite powder, and natural flake graphite, through processes such as calcination, molding, and roasting. Patent CN 114292106 B (publication date: May 26, 2023) discloses a method for rapidly converting coal into high-quality graphite. This method uses powdered coal as raw material, which is dry-milled, pressed into blocks, and sintered under high temperature and pressure to obtain high-quality graphite. Coal is a natural fossil fuel and a non-renewable energy source, making the raw material limited. Furthermore, this patent employs a high-temperature and high-pressure environment, with pressures reaching 2-6 GPa, thus requiring high-performance equipment with high temperature and pressure resistance. In addition, the sample volume processed in this patent is very limited, producing only less than 5g of high-quality graphite sample at a time.

[0005] Therefore, how to provide a method for producing high-quality graphite suitable for sealing materials using waste as raw material is an urgent problem to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing high-quality graphite using forestry waste and the resulting graphite, which can make full use of forestry waste resources and obtain high-quality graphite with high purity, high thermal conductivity and electrical conductivity, and is suitable for sealing materials.

[0007] In a first aspect, the present invention provides a method for preparing high-quality graphite using forestry waste, comprising the following steps:

[0008] Pretreatment: The dried forestry waste is crushed and pretreated.

[0009] Activation: After mixing the pulverized forestry waste with a solid oxidant, activate it by keeping it at an inert gas atmosphere of 400-600℃.

[0010] Carbonization: The activated sample is placed in an inert gas environment at 800-1000℃ for carbonization;

[0011] High-temperature graphitization: The carbonized sample is rinsed with water, dried, and then mixed with a high-temperature graphitization catalyst for high-temperature graphitization treatment at 2500-3000℃.

[0012] Post-processing: The sample after high-temperature graphitization treatment is sequentially washed with water, sieved, soaked in acid solution, washed with water, dried, and ball-milled to obtain the final product.

[0013] Preferably, the solid oxidant is selected from potassium permanganate and manganese dioxide; the mass ratio of the pulverized forestry waste to the solid oxidant is 3 to 8:1.

[0014] Preferably, in the step of heat preservation and activation in an inert gas atmosphere at 400-600°C, the inert gas is selected from one or both of nitrogen or argon, and the heat preservation and activation time is 40-50 hours.

[0015] Preferably, in the carbonization step, the inert gas is selected from one or both of nitrogen and argon, and the carbonization time is 1 to 2 hours.

[0016] Preferably, inorganic salts are added during the carbonization step; the mass ratio of the activated sample to the inorganic salts is 1:3 to 5.

[0017] Furthermore, the inorganic salt is selected from one of sodium chloride, potassium chloride, calcium chloride, ferric chloride, and zinc chloride.

[0018] Preferably, the high-temperature graphitization catalyst is selected from Al2SiO5 and SiO2; the ratio of the carbonized sample to the high-temperature graphitization catalyst is 40-60:1.

[0019] Preferably, the high-temperature graphitization treatment takes 5 to 8 hours.

[0020] Preferably, during the high-temperature graphitization process, argon is used as a protective gas at a pressure of 40–60 kPa.

[0021] Preferably, in the post-processing step, the sieve aperture is 1-3 mm, the acid solution is selected from sulfuric acid, hydrochloric acid or nitric acid solution, the soaking time is 1-3 h, the drying temperature is 100-120℃, and the drying time is 20-30 h.

[0022] Preferably, the solvent for ball milling is ethanol, the ball milling speed is 300-400 r / min, and the ball milling time is 0.5-1 h; the ball milling step is followed by a drying step, the drying temperature is 60-100℃, and the drying time is 5-12 h.

[0023] Secondly, the present invention provides high-quality graphite prepared by the above method; the purity of the high-quality graphite is above 99%.

[0024] Thirdly, the present invention provides the application of the above-mentioned high-quality graphite in graphite sealing materials.

[0025] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0026] This invention obtains high-quality graphite with a purity of up to 99% by activating, carbonizing, high-temperature graphitizing, and post-processing forestry waste. The resulting graphite product has good thermal conductivity, electrical conductivity, and mechanical properties, making it suitable for the preparation of graphite sealing materials and realizing the high-value utilization of forestry waste. In addition, this invention has high production capacity and large processing volume, capable of processing 400-800g of samples at a time. Attached Figure Description

[0027] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0028] Figure 1 This is the Raman spectrum of the graphite powder prepared in Example 1 of this invention. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] This invention provides a method for preparing high-quality graphite using forestry waste, comprising the following steps:

[0031] Pretreatment: The dried forestry waste is crushed and pretreated.

[0032] Activation: After mixing the pulverized forestry waste with a solid oxidant, activate it by keeping it at an inert gas atmosphere of 400-600℃.

[0033] Carbonization: The activated sample is placed in an inert gas environment at 800-1000℃ for carbonization;

[0034] High-temperature graphitization: The carbonized sample is rinsed with water, dried, and then mixed with a high-temperature graphitization catalyst for high-temperature graphitization treatment at 2500-3000℃.

[0035] Post-processing: The sample after high-temperature graphitization treatment is sequentially washed with water, sieved, soaked in acid solution, washed with water, dried, and ball-milled to obtain the final product.

[0036] In existing technologies, the raw materials for preparing high-quality graphite are generally substances with high carbon content (over 90%), such as petroleum coke, pitch coke, anthracite, graphite powder, and natural flake graphite, making them relatively easy to prepare graphite. However, this invention uses forestry waste as raw material, which has a carbon content of only 40-60%, making the preparation of high-quality graphite more challenging.

[0037] This invention first involves activating pulverized forestry waste with a solid oxidant at 400–600°C. This step improves the crystallinity and purity of graphite and increases its surface active sites. The oxidant introduces oxygen atoms into the structure of carbon materials, forming oxygen functional groups such as hydroxyl (-OH), carbonyl (-COOH), and ketone (-C=O). These functional groups increase the polarity of the carbon material surface and provide more active sites, affecting its chemical reactivity. Oxidation can also introduce more surface defects or active sites, increasing available sites in the reaction and facilitating the adsorption of substances or serving as a catalyst carrier. The solid activator, through surface oxidation, can form more active sites or functional groups during graphitization, which is of great significance for improving the properties of graphite, increasing its functionality, and adapting it to different applications. During the activation process, forestry waste is exposed to a high-temperature inert gas environment. Under these conditions, some organic matter undergoes pyrolysis reactions, including the volatilization or decomposition of carbon oxides and the breaking of bonds within organic molecules, producing gaseous products and residual solid carbon. The carbon produced can be further utilized during the carbonization process.

[0038] In the subsequent carbonization step, organic matter undergoes pyrolysis and carbonization under anaerobic conditions, resulting in a carbon content of up to 99% in the carbonized sample. The carbonized sample is then rinsed with water to remove soluble impurities and dried before being mixed with a high-temperature graphitization catalyst. This high-temperature graphitization catalyst reduces the energy required for the conversion of carbon materials into graphite. This means that at a given temperature, adding a catalyst can accelerate the conversion of carbon materials to graphite because the catalyst lowers the energy threshold required for the reaction. Silicate catalysts can act as nuclei or provide lattice templates, influencing the growth and arrangement of graphite crystals, and consequently affecting their morphology, size, and structure. The catalyst can affect the growth rate of graphite crystals. The addition of a catalyst alters the rate of carbon atom deposition or rearrangement, thus affecting the size and morphology of graphite crystals, thereby contributing to the acquisition of higher quality graphite.

[0039] Following the high-temperature graphitization step, this invention removes soluble impurities by washing with water. Sieving is used to separate and remove particles, residual impurities, or potential aggregates from the material, resulting in a purer and more homogeneous sample. While washing removes soluble impurities, some water-insoluble residual impurities may still remain. The sieving process helps separate and remove these residual particles or impurities. After sieving, some difficult-to-remove impurities may still remain in the sample, such as oxides, partially water-soluble impurities, or other surface-adsorbed impurities. Immersion in an acid solution helps dissolve these residual impurities, making them easier to remove; the acid solution also cleans the surface, removing any oxide layers, deposits, or other impurities, resulting in a purer sample surface.

[0040] The invention further employs ball milling, where ethanol helps disperse graphite particles, preventing re-aggregation and resulting in a more uniform dispersion of the particles in the solution. This further cleans the graphite surface, removing residual acidic solution or other potential impurities. Ethanol, as a solvent, also provides lubrication, reducing frictional resistance between graphite particles and enhancing the ball milling effect, thus promoting sample homogenization. This further improves sample purity, dispersibility, and surface properties, thereby enhancing the usability and adaptability of the graphite material. The above steps enable the conversion of forestry waste into high-quality graphite.

[0041] In this invention, the solid oxidant is selected from potassium permanganate and manganese dioxide; the mass ratio of the pulverized forestry waste to the solid oxidant is 3-8:1. A suitable mass ratio ensures sufficient activation of the forestry waste, thereby improving the quality of subsequent treatment.

[0042] In this invention, during the activation step in an inert gas atmosphere at 400–600°C, the inert gas is selected from one or both of nitrogen and argon, and the activation time is 40–50 hours. A longer activation time ensures the removal of residual impurities, improves the purity and quality of the waste, increases reactive sites, and enhances the reactivity of the waste in subsequent treatments.

[0043] In this invention, during the carbonization step, the inert gas is selected from one or both of nitrogen and argon, and the carbonization time is 1-2 hours. Since a relatively long activation step at 400-600°C has already been performed before the carbonization step, most of the organic matter is pyrolyzed, eliminating factors that could affect subsequent processes. The carbon produced by the pyrolysis of the organic matter can also be further utilized during the graphitization process.

[0044] In the carbonization step of this invention, an inorganic salt may also be added, selected from sodium chloride, potassium chloride, calcium chloride, ferric chloride, and zinc chloride. The aforementioned inorganic salts possess good high-temperature resistance and melt at the carbonization temperature of this invention, forming a molten salt bath, thereby ensuring more uniform heating of the sample. In this invention, the mass ratio of the activated sample to the inorganic salt is 1:3 to 5. The inorganic salt can be removed by a subsequent water washing step.

[0045] This invention does not impose any special limitations on the high-temperature graphitization catalyst; any commonly used high-temperature graphitization catalyst in the art can be used. Preferably, the catalyst is selected from Al2SiO5 or SiO2. This type of catalyst can act as a catalyst at high temperatures, lowering the reaction energy barrier of graphitization, accelerating the transformation of carbon materials into graphite, and increasing the graphitization rate. The addition of the catalyst also helps to lower the surface energy of graphite crystals, making the crystals more stable, reducing surface defects, and improving the stability and crystallinity of graphite. Silicate catalysts can act as nuclei for graphite crystals, providing a starting point on their surface, which helps in the formation and growth of graphite crystals. This helps to control the size, morphology, and structure of graphite crystals.

[0046] In this invention, the high-temperature graphitization treatment lasts for 5–8 hours, and argon is used as the protective gas during the process, with a pressure of 40–60 kPa. This invention does not require a high-pressure environment; graphitization can be completed under high-temperature calcination conditions. During graphitization, the carbon material gradually transforms from an amorphous state or a state with low crystallinity to a more crystalline state. Initially, the carbon material may be amorphous or have low crystallinity. At high temperatures, with the extension of heat treatment time, its structure gradually transforms into a more ordered graphite structure. As the heat treatment time increases, the arrangement between atoms or molecules may become more ordered, and the crystal lattice structure will gradually improve, leading to an increase in crystallinity. Under high-temperature conditions, carbon atoms rearrange to form hexagonal graphite layers. These layers are stacked in parallel to form a graphite crystal structure. As the graphitization process proceeds, the interaction between graphite layers and the crystallinity increase, and the crystal form and structure of graphite become more stable.

[0047] In the post-processing step of this invention, the sieve aperture is 1-3 mm, the acid solution is selected from sulfuric acid, hydrochloric acid or nitric acid solution, the soaking time is 1-3 h, the drying temperature is 100-120℃, and the drying time is 20-30 h.

[0048] In this invention, the solvent for ball milling is ethanol, the ball milling speed is 300-400 r / min, and the ball milling time is 0.5-1 h; after the ball milling step, a drying step is also included, with a drying temperature of 60-100℃ and a drying time of 5-12 h.

[0049] The present invention also provides high-quality graphite prepared by the above method; the purity of the high-quality graphite is above 99%.

[0050] This invention also provides the application of the aforementioned high-quality graphite in graphite sealing materials. Graphite materials prepared from forestry waste are particularly suitable for graphite sealing materials compared to traditional graphite materials (such as natural graphite) or graphite materials obtained by other preparation methods, mainly for the following reasons: ① Microstructure advantage: Graphite materials prepared from forestry waste have a finer and more uniform microstructure, containing more nanoscale graphite particles. This structure may provide more active sites and surface reaction areas; ② Purity advantage: After fine processing and synthesis, the graphite materials prepared from forestry waste have a purity of over 99%. Higher purity materials can reduce impurities or defects, thereby improving their physical properties and chemical stability; ③ Superior thermal conductivity: Due to its layered structure and special molecular arrangement, the prepared graphite material has excellent thermal conductivity, exceeding 150 W / m·K. High thermal conductivity graphite sealing materials can be used in high-temperature environments, helping to quickly conduct and disperse heat, improving the thermal stability of the sealing system; ④ Excellent electrical conductivity: The graphite material prepared in this invention has an electrical conductivity of 2.8 × 10⁻⁶. 5 With a conductivity of S / m or higher, graphite materials with high conductivity can be used for conductive sealing in sealing applications, which helps to eliminate or reduce resistance and ensure smooth current transmission; ⑤ Sustainability advantages: Graphite materials made from forestry waste are sustainable and environmentally friendly, meeting the needs of modern society for green materials, and have lower production costs.

[0051] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0052] Example 1

[0053] This embodiment provides a method for preparing high-quality graphite using forestry waste:

[0054] (1) The collected forestry waste was thoroughly washed three times with deionized water and dried in an oven at 120°C for 24 hours. After being taken out, it was cooled at room temperature for later use. The dried sample was then crushed in a pulverizer for later use.

[0055] (2) Take out 800g of the crushed forestry waste sample and add 160g of potassium permanganate. After mixing evenly, put it into an activation furnace with nitrogen gas. Set the temperature to 500℃ and heat it at a rate of 5-8℃ / min. Keep it warm for 48h and then take it out and cool it to room temperature for later use.

[0056] (3) Place the sample in a high-temperature tube furnace, set the temperature to 800℃, introduce nitrogen gas, maintain the high temperature for 3 hours, take it out and cool it at room temperature for about 12 hours for later use.

[0057] (4) Take out 500g of the prepared sample and 10g of Al2SiO5 and put them into a high-temperature graphitization furnace. Set the temperature to 2500℃, introduce argon gas to remove the air in the furnace, and keep the pressure at 50kPa. Start the heating program and control the heating rate at 5℃ / min. After heating to the set temperature, keep it at the temperature for 5h, cool it to room temperature, and solidify it to form a high-quality graphite structure.

[0058] (5) The obtained sample was washed with water 4 times, dried, filtered with a 2mm sieve, and then soaked and stirred in a 30% hydrochloric acid solution for 2 hours. The product was washed with deionized water 5 times and then dried in a 100℃ oven for 24 hours. The product was washed with deionized water 3 times to obtain 400g of graphite sample.

[0059] (6) Add 400g of the prepared graphite and 150mL of ethanol to a ball mill with a speed of 350r / min for grinding. After grinding, the powder is dried (in an oven at 110℃) to obtain the graphite product.

[0060] Figure 1 The Raman spectrum of the graphite powder prepared in this embodiment is shown at 1580 cm⁻¹. -1 The G peak at 2897 cm⁻¹ suggests the relative integrity of the graphite crystal structure, and its relative intensity indicates the order and regularity of the lattice in the sample. -1 The 2D peak at the location provides more information about the graphite stacking, indicating that the graphene has a multilayered graphite structure, suggesting a high degree of graphitization.

[0061] Example 2

[0062] This embodiment provides a method for preparing high-quality graphite using forestry waste:

[0063] (1) The collected forestry waste was thoroughly washed three times with deionized water and dried in an oven at 120°C for 24 hours. After being taken out, it was cooled at room temperature for later use. The dried sample was then crushed in a pulverizer for later use.

[0064] (2) Take out 800g of the crushed forestry waste sample and add 160g of manganese dioxide. After mixing evenly, put it into an activation furnace with nitrogen gas. Set the temperature to 450℃ and heat it at a rate of 5-8℃ / min. Keep it warm for 50h and then cool it to room temperature for later use.

[0065] (3) Place the sample in a high-temperature tube furnace, set the temperature to 900℃, introduce nitrogen gas, maintain the high temperature for 3 hours, take it out and cool it at room temperature for 12 hours for later use.

[0066] (4) Take out 500g of the prepared sample and 10g of SiO2 and put them into a high-temperature graphitization furnace. Set the temperature to 2700℃. After purging the air in the furnace with argon, keep the pressure at 50kPa. Start the heating program and control the heating rate at 5℃ / min. After heating to the set temperature, keep it at the temperature for 5h and then cool it to room temperature. After solidification, a high-quality graphite structure is formed.

[0067] (5) The obtained sample was washed with water 4 times, dried, filtered with a 2mm sieve, and then soaked and stirred in a 30% hydrochloric acid solution for 2 hours. The product was washed with deionized water 5 times and then dried in a 100℃ oven for 24 hours. The product was washed with deionized water 3 times to obtain 400g of graphite sample.

[0068] (6) Add 400g of the prepared graphite and 150mL of ethanol to a ball mill with a speed of 350r / min for grinding. After grinding, the powder is dried (in an oven at 110℃) to obtain the graphite product.

[0069] Example 3

[0070] Compared with Example 1, the difference is that step (3) in this example is:

[0071] The sample and a 2000g industrial sodium chloride ceramic crucible were placed in a high-temperature box furnace, the temperature was set to 800℃, nitrogen gas was introduced, and the high temperature was maintained for 3 hours. After being removed, the sample was cooled to room temperature for about 12 hours for later use.

[0072] Comparative Example 1

[0073] Compared with Example 1, the difference is that this comparative example does not undergo the activation step (2). The specific steps are as follows:

[0074] (1) The collected forestry waste was thoroughly washed three times with deionized water and dried in an oven at 120°C for 24 hours. After being taken out, it was cooled at room temperature for later use. The dried sample was then crushed in a pulverizer for later use.

[0075] (2) Take out 800g of the crushed forestry waste sample and put it into a high-temperature tube furnace. Set the temperature to 800℃, introduce nitrogen, and maintain the high temperature for 24 hours. After taking it out, cool it at room temperature for about 12 hours for later use.

[0076] (3) Take out 500g of the prepared sample and 10g of Al2SiO5 and put them into a high-temperature graphitization furnace. Set the temperature to 2500℃, introduce argon gas to remove the air in the furnace, and keep the pressure at 50kPa. Start the heating program and control the heating rate at 5℃ / min. After heating to the set temperature, keep it at the temperature for 5h, cool it to room temperature, and solidify it to form a graphite structure.

[0077] (4) The obtained sample was washed with water 4 times, dried, filtered with a 2mm sieve, and then soaked and stirred with a 30% hydrochloric acid solution for 2 hours. The product was washed with deionized water 5 times and then dried in a 100℃ oven for 24 hours. The product was washed with deionized water 3 times to obtain 400g of graphite sample.

[0078] (5) Add 400g of the prepared graphite and 150mL of ethanol to a ball mill with a speed of 350r / min for grinding. After grinding, the powder is dried (in an oven at 110℃) to obtain the graphite product.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 1 is that the heat preservation and activation time is 24 hours.

[0081] Test case

[0082] The performance of the graphite products of Examples 1-3 and Comparative Examples 1-2 was measured, and the results are shown in Table 1.

[0083] Table 1. Performance test results of graphite products from Examples 1-3 and Comparative Examples 1-2.

[0084]

[0085]

[0086] The data in the table show that the graphite prepared in Examples 1 and 2 possesses the best overall performance. Example 3 demonstrates that while the molten salt bath process does not affect the purity and electrical conductivity of the graphite, it does cause a decrease in flexural strength and thermal conductivity. However, the graphite prepared in all three examples meets the requirements for preparing sealing materials. Comparative Example 1 illustrates the necessity of the activation process in the preparation of graphite from forestry waste. Without the heat preservation activation process, purity, flexural strength, and thermal conductivity all decrease to varying degrees. Furthermore, Comparative Example 2 shows that shortening the activation time also prevents the obtained sample from meeting the requirements for preparing sealing materials.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing high-quality graphite for a graphite sealing material using forestry waste, characterized by, It comprises the following steps: Pre-treatment: dry forestry waste is crushed and pre-treated; Activation: the crushed forestry waste is mixed with a solid oxidizing agent, and then activated in an inert gas atmosphere at 400-600℃ for 40-50h; The solid oxidizing agent is selected from one of potassium permanganate and manganese dioxide; the mass ratio of the crushed forestry waste to the solid oxidizing agent is 3-8:1; Carbonization: the activated sample is carbonized in an inert gas environment at 800-1000℃; the carbonization time is 1-2h; High-temperature graphitization: the carbonized sample is rinsed with water, dried, mixed with a high-temperature graphitization catalyst, and then subjected to high-temperature graphitization treatment at 2500-3000℃; the high-temperature graphitization treatment time is 5-8h; The high-temperature graphitization catalyst is selected from one of Al2SiO5 and SiO2; in the high-temperature graphitization process, argon is used as the protective gas, and the pressure is 40-60 kPa; Post-treatment: the high-temperature graphitization treated sample is sequentially subjected to water washing, screening, acid solution immersion, water washing, drying, and ball milling, thereby obtaining high-quality graphite; the purity of the high-quality graphite is above 99%.

2. The method of claim 1, wherein, In the step of activation in an inert gas atmosphere at 400-600℃, the inert gas is selected from one or both of nitrogen and argon.

3. The method of claim 1, wherein, In the carbonization step, the inert gas is selected from one or both of nitrogen and argon.

4. The method of claim 1, wherein, The use amount ratio of the carbonized sample to the high-temperature graphitization catalyst is 40-60:

1.

5. The method of claim 1, wherein, In the post-treatment step, the screen aperture is 1-3mm, the acid solution is selected from one of sulfuric acid, hydrochloric acid, or nitric acid solution, the immersion time is 1-3h; the drying temperature is 100-120℃, and the drying time is 20-30h.

6. The method of claim 1, wherein, The ball milling solvent is ethanol, the ball milling rotation speed is 300-400r / min, and the ball milling time is 0.5-1h; the ball milling step is followed by a drying step, the drying temperature is 60-100℃, and the time is 5-12h.

7. High quality graphite produced by the process according to any one of claims 1 to 6, characterized in that The purity of the high-quality graphite is above 99%.

8. Use of the high-quality graphite according to claim 7 in graphite sealing materials.

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