Method for producing graphite with volumetric heating, product and its application in heating device

Abstract

FIELD: graphite with volumetric heating.SUBSTANCE: method for producing volume-heated graphite, wherein the volume-heated graphite has a specific resistance of 50 mcOhm⋅m or higher, and a resistance value of 0.5 ohms or higher, so that the supply of electric energy from both ends allows the entire graphite part to generate heat, includes the following steps: weighing a powder material and a binder, wherein the powder material is pitch coke and the binder is modified pitch; preheating the weighed pitch coke; heating the modified pitch to a molten state; pouring the modified pitch in a molten state into the preheated pitch coke and stirring to obtain a paste; extracting the paste and performing hot rolling, cooling, grinding and sieving on the paste to obtain a mixed powder; isostatically pressing molding the mixed powder to form a sample in the form of a blank; and performing two calcination treatments on the molded sample in the form of a blank to obtain a volumetrically heated graphite sample.EFFECT: provides graphite that has heating resistance and generates heat evenly when power is supplied, resulting in more sufficiently heated air, higher temperature uniformity and better heating effect, satisfying the vaping requirements of heated cigarette and creating uniform smoke flavor from puff to puff.7 cl, 5 dwg, 1 tbl

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The present invention relates to the technical field of heating devices with heating without combustion, in particular to a method for producing graphite with volumetric heating, a product and its use in a heating device. BACKGROUND

[0002] Currently available combustion-free heating devices use airflow heating. Airflow heating technology (such as bottom-heating) generally uses a filament or heating needle to first heat itself and then heat a heat-conducting component connected to it, rapidly raising the temperature of the heat-conducting component. The heat dissipates around it, heating the air passing through. The heated air then enters the tobacco rod, heating the tobacco rod and generating smoke. In this heating method, the closer the heat source (such as the filament, heating rod, etc.), the higher the temperature, and the farther it is from the heat source, the lower the temperature. As a result, the air used to heat the tobacco rod has a significant temperature difference, resulting in unsatisfactory heating results.

[0003] Therefore, there is a need to provide a method for producing graphite with volumetric heating, a product and its use in a heating device. SUMMARY OF THE INVENTION

[0004] The aim of the present invention is to provide a method for producing volumetrically heated graphite, a product, and its use in a heating device to solve the above-mentioned problems in the prior art. Graphite itself is characterized by resistance, ensuring heating, uniformly generating heat when electrical energy is supplied, thereby creating sufficiently heated air with uniform temperature distribution and improved heating effects.

[0005] The present invention provides a method for producing graphite with volumetric heating, comprising the following steps:

[0006] weighing the powder material and the binder, wherein the powder material is pitch coke and the binder is modified pitch;

[0007] preheating of suspended pitch coke;

[0008] Heating the modified pitch to a molten state;

[0009] Pouring the modified pitch in a molten state into the preheated pitch coke and stirring to form a paste;

[0010] extracting the paste and performing hot rolling, cooling, grinding and sieving on the paste to obtain a mixed powder;

[0011] isostatically pressing the mixed powder to form a sample in the form of a blank; and

[0012] Carrying out two firing treatments on a molded sample in the form of a blank to obtain a graphite sample with volumetric heating.

[0013] In the method for producing graphite with volumetric heating according to the above, preferably the step of weighing the powder material and the binder, in particular, includes:

[0014] weighing the modified pitch, wherein the proportion of the modified pitch in the mixture of pitch coke and modified pitch is in the range of 23% to 28%; and

[0015] weighing pitch coke, wherein the pitch coke is a sieved powder with a particle size in the range of 200 mesh to 325 mesh.

[0016] In the method for producing graphite with volumetric heating according to the above, preferably the step of preheating the suspended pitch coke, in particular, includes:

[0017] pouring the weighed pitch coke into the stirring tank for preheating, wherein the preheating temperature is in the range of 150 °C to 180 °C, and the preheating time is in the range of 50 minutes to 70 minutes; and

[0018] the step of heating the modified pitch to a molten state, in particular, includes:

[0019] Heating the modified pitch to a temperature equal to or greater than 200°C to change the modified pitch from a solid state to a molten state.

[0020] In the method for producing graphite with volumetric heating according to the above, preferably the step of pouring modified pitch in a molten state into preheated pitch coke and stirring, in particular, includes:

[0021] pouring modified pitch in a molten state into a stirring tank and stirring the modified pitch with preheated pitch coke, wherein the stirring time is in the range of 40 minutes to 50 minutes, and the stirring temperature is in the range of 170 °C to 190 °C.

[0022] In the method for producing graphite with volumetric heating according to the above, preferably the step of extracting the paste and performing hot rolling, cooling, grinding and sieving on the paste to obtain a mixed powder, specifically includes:

[0023] Taking out the paste from the stirring tank after stirring and feeding it into the hot rolling machine for rolling the paste twice at a temperature in the range of 160°C to 190°C;

[0024] natural cooling of paste;

[0025] grinding the paste after the paste is naturally cooled; and

[0026] Sieving the ground paste to a particle size of less than 100 mesh to obtain mixed powder.

[0027] In the method for producing graphite with volumetric heating according to the above, preferably the step of isostatic pressing molding of the mixed powder to form a sample in the form of a blank, in particular, includes:

[0028] loading the mixed powder into a steel mold and pre-forming the mixed powder on a hydraulic four-column press, wherein the pre-forming pressure is in the range of 18 MPa to 22 MPa, and the bulk density of the pre-formed part is in the range of 1.17 / cm 3 up to 1.21 / cm 3 ; And

[0029] Demolding the preformed part from the hydraulic four-column press, placing the preformed part in a rubber shell, and then isostatically pressing the preformed part under a pressure ranging from 110MPa to 130MPa.

[0030] In the method for producing graphite with volume heating according to the above, preferably the step of performing two firing treatments on a molded sample in the form of a blank to obtain a graphite sample with volume heating, in particular, includes:

[0031] performing a first firing treatment on a molded sample in the form of a blank to obtain a first-fired sample;

[0032] performing impregnation treatment on the sample that has undergone the first firing; and

[0033] performing a second firing treatment on the impregnated sample that has undergone the first firing to obtain a volumetrically heated graphite sample.

[0034] In the method for producing graphite with volumetric heating according to the above, preferably the step of performing, with respect to the formed sample in the form of a blank, a first treatment by firing, specifically includes:

[0035] performing a first firing treatment on a molded sample in the form of a blank in a box-type resistance furnace at a first firing temperature in the range of 880°C to 920°C, maintaining this temperature for 50 minutes to 70 minutes, naturally cooling to room temperature to obtain a first-fired sample,

[0036] The step of performing impregnation treatment on the sample that has undergone the first firing, in particular, includes:

[0037] Removing the sample that has passed the first firing from the box-type resistance furnace;

[0038] heating and melting the conductive binder; and

[0039] immersing the specimen which has undergone the first firing into the molten conductive binder for impregnation treatment, and at the same time

[0040] the step of performing, with respect to the impregnated sample that has undergone the first firing, a second firing treatment to obtain a volumetrically heated graphite sample, specifically includes:

[0041] Performing a second firing treatment on an impregnated specimen that has undergone the first firing in a box-type resistance furnace at a temperature in the range of 1800°C to 2000°C, maintaining this temperature for 50 minutes to 70 minutes, and naturally cooling to room temperature to obtain a volume-heated graphite specimen.

[0042] The present invention also provides volumetrically heated graphite obtained by the production method mentioned above.

[0043] The present invention also proposes the use of volume-heated graphite in a heating device. The method of use comprises placing copper rings on the upper end and lower end of volume-heated graphite, respectively, and supplying electrical energy to the copper rings, thereby generating heat.

[0044] Compared with the indirect heating method with a diffuser, the method for producing volumetrically heated graphite, the product, and its use in a heating device proposed in the present invention make it possible to produce graphite in a honeycomb shape as a whole, having a resistance that ensures heating, which generates heat uniformly when electric energy is supplied, so as to create sufficiently heated air with a uniform temperature distribution and improved heating effects. The specific resistance of the volumetrically heated graphite can reach 50 μΩ⋅m or more, and the resistance value of the volumetrically heated graphite can reach 0.5 μΩ⋅m or more, which ensures volumetric heating, and the supply of electric energy from both ends allows the entire part to generate heat, thereby satisfying the requirement for heating a tobacco rod for smoking.Air flowing through the volumetrically heated graphite can be heated completely, and the air temperature is uniform, resulting in remarkable tobacco rod heating and a consistent smoke flavor with every puff. Unlike traditional methods, there's no need to combine the porous honeycomb diffuser with other heating elements, making assembly more convenient. BRIEF DESCRIPTION OF GRAPHIC MATERIALS

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described with reference to the accompanying drawings.

[0046] Fig. 1 is a longitudinal sectional view showing a graphite-heated honeycomb diffuser as a resistive heating element.

[0047] Fig. 2 shows the diffraction pattern of the C-phase of graphite.

[0048] Fig. 3 is a schematic diagram showing the relationship between the resistivity and the degree of graphitization of a graphitized product.

[0049] Fig. 4 shows a flow chart of a method for producing graphite with volumetric heating according to an embodiment proposed in the present invention.

[0050] Fig. 5 shows a longitudinal sectional view of graphite with volumetric heating. DETAILED DESCRIPTION

[0051] Next, various illustrative embodiments of the present invention will be described in detail with reference to the accompanying drawings. The description of the illustrative embodiments is merely illustrative and is not intended to limit the present invention, its application or use in any way. The present invention can be implemented in a variety of different forms, which are not limited to the embodiments described herein. These embodiments are provided in order to make the description of the present invention complete and thorough and to fully convey the scope of legal protection of the present invention to those skilled in the art. It should be noted that the relative positions of the components and steps, the material composition, numerical expressions and numerical values ​​​​set forth in these embodiments, unless specifically stated otherwise, should be construed as illustrative only and not as limiting.

[0052] The use of the words "first," "second," and the like in the present invention does not denote any order, quantity, or priority, but is merely intended to distinguish various parts. Words such as "comprises," "includes," or variations thereof mean that the element before the word encompasses the element(s) listed after the word, without excluding the possibility of also encompassing other elements. The words "up," "down," and the like are used only to represent a relative positional relationship, and the relative positional relationship may be correspondingly changed by changing the absolute position of the described object.

[0053] In the present invention, if a specific component is described as being located between a first component and a second component, there may be an intermediate component between the specific component and the first component or the second component, and alternatively, the intermediate component may be absent. If a specific component is described as being connected to other components, the specific component may be directly connected to said other components without an intermediate component, and alternatively, it may not be directly connected to said other components, but with the help of an intermediate component.

[0054] All terms (including technical and scientific terms) used in this application have the same meaning as understood by those skilled in the art with respect to the present invention, unless otherwise defined. It should also be understood that terms with the meanings defined in generally accepted dictionaries, unless explicitly defined herein, should be construed as having meanings that correspond to their meanings in the context of the given art and should not be interpreted in an idealized or exclusively formalized sense.

[0055] Methods, techniques, and devices known to those of ordinary skill in the art may not be discussed in detail, but where necessary, these methods, techniques, and devices should be considered part of this description.

[0056] Current airflow heating technology (such as bottom-up air heating) heats the air through a porous honeycomb diffuser and then heats the tobacco rod with the heated air. In this method, the closer the heat source (such as a filament, heating rod, etc.), the higher the temperature, and the further the heat source is from the heat diffuser, the lower the temperature. To address this issue, materials with high thermal conductivity are used to minimize the temperature difference as much as possible, ensuring a uniform air temperature for heating the tobacco rod.

[0057] The currently used graphite for airflow heating, as a honeycomb heat dissipator, is shown in Fig. 1. It requires high thermal conductivity and low heat capacity. Graphite is, of course, a thermally conductive material with excellent properties. However, the resistivity of the currently used porous honeycomb graphite is very low, with a resistance value of less than 0.1 ohms, making it difficult to achieve volumetric heating.

[0058] In the present invention, the graphite formula used as a heat dissipator is modified to make the graphite's resistance value equal to or higher than 0.5 ohms, so that the graphite itself has a specific resistance value. For example, the graphite as a whole can have a resistance value in the range of 0.5 ohms to 3 ohms, enabling volumetric heating, wherein the supply of electrical energy from both ends allows the entire graphite part to generate heat, satisfying the heating conditions of a tobacco rod for smoking. The specific resistance of ordinary graphite is approximately 10 μΩ⋅m, while the specific resistance of the heating graphite obtained by the method of the present invention is in the range of 50 μΩ⋅m to 500 μΩ⋅m.

[0059] The microstructure analysis and physicochemical characteristics of graphite products during the graphitization heat treatment process are evaluated by measuring the parameter g to roughly estimate the degree of graphitization of graphite products. The degree of graphitization refers to the degree to which carbon atoms form a closely packed hexagonal crystalline structure of graphite. The closer the lattice size is to the lattice constant of ideal graphite, the higher the degree of graphitization. The graphitization process of amorphous carbon transforming into graphite is a transition from an amorphous to a crystalline state, and crystallinity is indicated by the degree of graphitization (i.e., parameter g).

[0060] Fig. 2 shows the diffraction pattern of the C-phase of graphite, with CuK αwas used as an X-ray source, and the wavelength λ of the X-rays was 0.154 nm. Based on the angle 2θ corresponding to the characteristic peak of the crystallographic plane (002) in the diffraction pattern in Fig. 2, the interlayer distance d 002 calculated using the full width at half maximum method according to Bragg's law (2d 002 sinθ=λ). The result was then substituted into the Merring–Meyer formula: to approximately calculate the degree of graphitization of a graphite product.

[0061] For example, the specific calculation process and results are as follows: .

[0062] The relationship between the resistivity and the degree of graphitization is shown in Fig. 3. As can be seen from Fig. 3, the resistivity of the samples at room temperature tends to decrease with the increase of the degree of graphitization (i.e., parameter g). Graphite-based carbon materials have a flat hexagonal carbon structure. Due to the differences in the graphite structures, their properties with respect to electron mobility within the layer plane are significantly different. According to the formula at room temperature the distance between layers is d 002Decreases with increasing degree of graphitization. In this case, the carrier concentration at grain boundaries, which is the main factor affecting the conductivity of carbon materials, increases with the simultaneous ordering of crystal grain boundaries, and the scattering effect is weakened, so that the conductivity of the sample increases and the resistivity of the sample decreases. A continuous increase in carrier concentration and a weakening of scattering at grain boundaries together result in a decrease in resistivity with increasing degree of graphitization.

[0063] It can be seen from Fig. 3 that in order to achieve a specific resistance of graphite equal to or greater than 50 μOhm⋅m, the degree of graphitization must be below 35%.

[0064] As shown in Fig. 4, the method for producing graphite with volumetric heating proposed in the embodiment may specifically include the following steps when implemented.

[0065] In step S1, the powder material and the binder are weighed, wherein the powder material is pitch coke and the binder is modified pitch.

[0066] The powder material mainly includes petroleum coke, pitch coke, isotropic coke, green coke, mesocarbon microspheres, and flake graphite powder, etc., as the main raw materials for producing graphite. Petroleum coke and pitch coke are generally used to produce graphite. Pitch coke is a high-quality coke with low ash content and is easily converted into graphite at high temperatures. Under the same high temperature condition, the graphitization degree of pitch coke is lower than that of petroleum coke, and the specific resistance of graphite obtained from pitch coke is higher than that of graphite obtained from petroleum coke. The main raw material used in the present invention is pitch coke, and in particular, it is calcined coal tar pitch.

[0067] In the embodiment of the method for producing graphite with volumetric heating according to the present invention, step S1 may specifically include step S11 and step S12.

[0068] In step S11, the modified pitch is weighed. The proportion of modified pitch in the pitch coke and modified pitch mixture ranges from 23% to 28%.

[0069] In some embodiments of the present invention, the proportion of modified pitch in the mixture is 25%. It should be noted that the present invention does not specifically provide for a limitation with respect to the proportion of pitch coke and the proportion of modified pitch in the mixture.

[0070] In step S12, the pitch coke is weighed. Pitch coke is a sieved powder with a particle size ranging from 200 mesh to 325 mesh.

[0071] For example, the particle size of pitch coke is 250 mesh. It should be noted that the present invention does not specifically limit the particle size of pitch coke.

[0072] In step S2, the weighed pitch coke is preheated.

[0073] Specifically, weighed pitch coke is poured into a mixing tank for preheating. The preheating temperature is in the range of 150°C to 180°C (e.g., 160°C), and the preheating time is in the range of 50 minutes to 70 minutes (e.g., 1 hour). It should be noted that the preheating temperature and preheating time of the pitch coke are not specifically limited in the present invention.

[0074] In step S3, the modified pitch is heated to a molten state.

[0075] Specifically, the modified pitch is heated to a temperature equal to or greater than 200°C to transform the modified pitch from a solid to a molten state. The weight of the modified pitch remains virtually unchanged during the transition from a solid to a molten state, meaning the weight loss is small and can be neglected.

[0076] In step S4, the modified pitch in a molten state is poured into the preheated pitch coke and stirred to form a paste.

[0077] Specifically, the modified pitch in a molten state is poured into a mixing tank and mixed with preheated pitch coke. The mixing time is in the range of 40 minutes to 50 minutes (e.g., 45 minutes), and the mixing temperature is in the range of 170°C to 190°C (e.g., 180°C). It should be noted that the mixing time and mixing temperature are not specifically limited in the present invention.

[0078] In step S5, the paste is taken out from the stirring tank and subjected to hot rolling, cooling, grinding and sieving to obtain a mixed powder.

[0079] In the embodiment of the method for producing graphite with volumetric heating according to the present invention, step S5 may specifically include steps S51, S52, S53 and S54.

[0080] In step S51, the paste is taken out from the stirring tank after the stirring treatment, fed to the rolling machine, and hot rolled twice at a temperature in the range of 160°C to 190°C.

[0081] In some embodiments of the present invention, the two hot rolling processes may be performed at the same temperature or at different temperatures, which is not particularly limited in the present invention.

[0082] In step S52, the paste is cooled naturally.

[0083] In step S53, the naturally cooled paste is subjected to grinding.

[0084] The paste can be ground by jaw crusher, ball mill, etc.

[0085] In step S54, the ground paste is sieved to a particle size of less than 100 mesh to obtain a mixed powder.

[0086] In step S6, the mixed powder is subjected to isostatic pressing and molding to form a sample in the form of a blank.

[0087] In the embodiment of the method for producing graphite with volumetric heating according to the present invention, step S6 may specifically include steps S61 and step S62.

[0088] In step S61, the mixed powder is loaded into a steel mold and pre-formed using a hydraulic four-column press. The pre-forming pressure is in the range of 18 MPa to 22 MPa (e.g., 20 MPa), and the bulk density of the pre-formed part is in the range of 1.17 / cm 3 up to 1.21 / cm 3 (for example, 1.19 / cm 3 ).

[0089] In step S62, the preformed part is removed from the hydraulic four-column press, placed in a rubber shell, and then isostatically pressed and molded under a pressure in the range of 110 MPa to 130 MPa (for example, 120 MPa).

[0090] In step S7, the molded sample in the form of a blank is subjected to two firing treatments to obtain a volumetrically heated graphite sample.

[0091] The resulting volume-heated graphite sample is shown in Fig. 5. In the embodiment of the volume-heated graphite production method according to the present invention, step S7 may specifically include steps S71, S72 and S73.

[0092] In step S71, the molded sample in the form of a blank is subjected to a first firing treatment to obtain a first-fired sample.

[0093] Specifically, with respect to a molded sample in the form of a blank, a first firing treatment is performed in a box-type resistance furnace at a first firing temperature in the range of 880°C to 920°C (for example, 900°C), held for 50 minutes to 70 minutes (for example, 1 hour), and naturally cooled to room temperature to obtain a first-fired sample.

[0094] In step S72, an impregnation treatment is performed on the sample that has undergone the first firing.

[0095] In the embodiment of the method for producing graphite with volumetric heating according to the present invention, step S72 may specifically include steps S721, S722 and S723.

[0096] In step S721, the sample that has undergone the first firing is removed from the box-type resistance furnace.

[0097] In step S722, the conductive binder is heated and melted.

[0098] In step S723, the sample which has undergone the first firing is dipped into the molten electrically conductive binder to undergo impregnation treatment.

[0099] In the impregnation process, graphite is impregnated with a binder, filling voids on the surface or within the graphite, and then the binder is cured through heat treatment. The present invention utilizes a heat-assisted impregnation process in which the conductive binder is heated to a predetermined temperature to melt it, and then the sample is immersed in it.

[0100] In step S73, a second firing treatment is performed on the impregnated sample that has undergone the first firing to obtain a volumetrically heated graphite sample.

[0101] Specifically, the impregnated specimen that has undergone the first firing is subjected to a second firing treatment in a box-type resistance furnace at a temperature in the range of 1800°C to 2000°C (e.g., 2000°C), held for 50 minutes to 70 minutes (e.g., 1 hour), and then naturally cooled to room temperature to obtain a volumetrically heated graphite specimen. During the first firing treatment, the modified pitch undergoes complex reactions of decomposition, polymerization, cyclization, and aromatization, releasing a significant amount of volatile substances. The volatilization of volatile substances creates a large number of voids in the part, which reduces the bulk density of the specimen. The bulk density of the specimen can be increased by impregnation and a second firing treatment.

[0102] The resistivity of the volume-heated graphite obtained by the above-described production method can reach 50 μΩ⋅m or more, and the resistance value of the volume-heated graphite can reach 0.5 Ω or more, achieving volumetric heating. Power is supplied from both ends, allowing the entire part to generate heat, thereby satisfying the heating requirements of the tobacco rod for smoking. Air flowing through the volume-heated graphite can be heated throughout, and the air temperature is uniform, resulting in excellent heating effects for the tobacco rod and a uniform smoke flavor with each puff.

[0103] In the embodiments of the present invention, three volume-heated graphite samples were obtained using the above production method. The processing conditions and specific resistance of each sample are shown in Table 1.

[0104] Table 1: Processing conditions and resistivity values ​​of samples 1-3 № Pitch content (%) First firing temperature (°C) Second firing temperature (°C) Specific resistance (μOhm⋅m) Sample 1 25 900 1800 50–58 Sample 2 25 900 2000 41–52 Sample 3 25 900 2200 38–47

[0105] According to Table 1, the specific resistance of sample 1 is the highest, ranging from 50 μΩ⋅m to 58 μΩ⋅m; the specific resistance of sample 2 is the second after it, ranging from 41 μΩ⋅m to 52 μΩ⋅m; and the specific resistance of sample 3 is the lowest, ranging from 38 μΩ⋅m to 47 μΩ⋅m. Therefore, the processing conditions of sample 1 are optimal conditions, which means that the second calcining temperature is preferably 1800 °C.

[0106] Also, in another embodiment of the present invention, volumetrically heated graphite is provided, which is obtained by the above-described production method.

[0107] Another embodiment of the present invention provides the use of volume-heated graphite in a heating device. The method of use comprises: placing copper rings on the upper end and lower end of the volume-heated graphite, respectively, and supplying electrical energy to the copper rings, thereby generating heat.

[0108] Compared with the indirect heating method with a diffuser, the method for producing volumetrically heated graphite, the product, and its use in a heating device proposed in the embodiments of the present invention make it possible to produce honeycomb-shaped graphite as a whole having a heating resistance that generates heat uniformly when electrical energy is supplied, so as to create sufficiently heated air with a uniform temperature distribution and improved heating effects. The specific resistance of the volumetrically heated graphite can reach 50 μΩ⋅m or more, and the resistance value of the volumetrically heated graphite can reach 0.5 Ω or more, which ensures volumetric heating, and the supply of electrical energy from both ends allows the entire part to generate heat, thereby satisfying the requirement for heating a tobacco rod for smoking.Air flowing through the volumetrically heated graphite can be heated completely, and the air temperature is uniform, resulting in remarkable tobacco rod heating effects and a consistent smoke flavor with every puff. Unlike traditional methods, there's no need to combine the porous honeycomb diffuser with other heating elements, making assembly more convenient.

[0109] Various embodiments of the present invention have been described in detail above. Certain details well known in the prior art have been omitted to avoid obscuring the concept of the present invention. Based on the description above, those skilled in the art will readily understand how to implement the technical solutions described herein.

[0110] Although some specific embodiments of the present invention have been described in detail as examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of protection of this application. Those skilled in the art should understand that modifications to the above embodiments and equivalent replacement of part of the technical features can be made without departing from the scope of protection and the spirit of this application. The scope of protection of this application is defined by the appended claims.

Claims

1. A method for producing volume-heated graphite, wherein the volume-heated graphite has a resistivity of 50 μΩ⋅m or higher and a resistance value of 0.5 Ω or higher, so that supplying electrical energy from both ends allows the entire graphite part to generate heat, wherein the method includes the following steps: weighing a powder material and a binder, wherein the powder material is pitch coke and the binder is modified pitch; preheating of suspended pitch coke; heating the modified pitch to a molten state; pouring the modified pitch in a molten state into preheated pitch coke and stirring to form a paste; extracting the paste and subjecting the paste to hot rolling, cooling, grinding and sifting to obtain a mixed powder; isostatically pressing the mixed powder to form a sample in the form of a blank; and performing two firing treatments on a formed sample in the form of a blank to obtain a sample of graphite with volumetric heating; wherein the stage of isostatic pressing of the mixed powder to form a sample in the form of a blank includes: loading the mixed powder into a steel mold and pre-forming the mixed powder on a hydraulic four-column press, wherein the pre-forming pressure is in the range of 18 MPa to 22 MPa, and the bulk density of the pre-formed part is in the range of 1.17 g / cm 3 up to 1.21 g / cm 3 ; And removing the preformed part from the hydraulic four-column press, placing the preformed part in a rubber shell, and then isostatically pressing the preformed part under a pressure in the range of 110 MPa to 130 MPa; wherein the step of performing two firing treatments on the formed sample in the form of a blank to obtain a graphite sample with volumetric heating includes: performing a first firing treatment on a formed sample in the form of a blank to obtain a sample that has undergone the first firing; performing impregnation treatment on the sample that has undergone the first firing; and performing a second firing treatment on the impregnated sample that has undergone the first firing to obtain a volumetrically heated graphite sample; the stage of performing the first processing by firing in relation to the formed sample in the form of a blank includes: performing a first firing treatment on a shaped sample in the form of a blank in a box-type resistance furnace at a first firing temperature in the range of 880 °C to 920 °C, maintaining this temperature for 50 minutes to 70 minutes, naturally cooling to room temperature to obtain a sample that has undergone the first firing, the stage of performing impregnation treatment on a sample that has undergone the first firing includes: removing the sample that has passed the first firing from the box-type resistance furnace; heating and melting the conductive binder; and immersion of the sample, which has undergone the first firing, into the molten conductive binder for impregnation treatment, and at the same time the step of performing, in relation to the impregnated sample that has undergone the first firing, the second firing treatment to obtain a graphite sample with volumetric heating includes: subjecting the impregnated sample that has undergone the first firing to a second firing treatment in a box-type resistance furnace at a temperature in the range of 1800 °C to 2000 °C, maintaining this temperature for 50 minutes to 70 minutes and naturally cooling to room temperature to obtain a volumetrically heated graphite sample.

2. The method according to paragraph 1, characterized in that the step of weighing the powder material and the binder includes: weighing the modified pitch, wherein the proportion of modified pitch in the mixture of pitch coke and modified pitch is in the range of 23% to 28%; and weighing pitch coke, wherein the pitch coke is a sieved powder with a particle size in the range of 200 mesh to 325 mesh.

3. The method according to paragraph 1, characterized in that the stage of preheating the suspended pitch coke includes: pouring the weighed pitch coke into a mixing tank for preheating, wherein the preheating temperature is in the range of 150 °C to 180 °C, and the preheating time is in the range of 50 minutes to 70 minutes; and the stage of heating the modified pitch to a molten state includes: heating the modified pitch to a temperature equal to or greater than 200 °C to transform the modified pitch from a solid state to a molten state.

4. The method according to claim 1, characterized in that the step of pouring modified pitch in a molten state into preheated pitch coke and stirring includes pouring modified pitch in a molten state into a stirring tank and stirring the modified pitch with preheated pitch coke, wherein the stirring time is in the range of 40 minutes to 50 minutes, and the stirring temperature is in the range of 170 °C to 190 °C.

5. The method according to paragraph 1, characterized in that the step of extracting the paste and performing hot rolling, cooling, grinding and sifting with respect to the paste to obtain a mixed powder includes: removing from the mixing tank after mixing and feeding the paste into the hot rolling machine for rolling the paste twice at a temperature in the range of 160°C to 190°C; natural cooling of paste; grinding the paste after natural cooling of the paste; and sieving the ground paste to a particle size of less than 100 mesh to obtain a mixed powder.

6. Volumetrically heated graphite having a specific resistance from 50 μOhm⋅m to 500 μOhm⋅m and a resistance value greater than or equal to 0.5 Ohm, obtained by the method according to any of paragraphs. 1-5.

7. The use of volumetrically heated graphite according to paragraph 6 in a heating device, which includes placing copper rings on the upper end and lower end of volumetrically heated graphite, respectively, and supplying electrical energy to the copper rings, thereby generating heat.

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