Method for preparing isostatic pressing graphite from waste graphite electrode

Abstract

The invention discloses a method for preparing isostatic pressing graphite from a waste graphite electrode. The method comprises the following steps: cleaning a waste graphite negative electrode, purifying, grinding, kneading, isostatic pressing, roasting and graphitizing. According to the present invention, the waste graphite negative electrode is adopted as the raw material, such that the production cost is reduced, the waste graphite negative electrode has good performance, the graphitization degree of the waste graphite negative electrode is high, the calcination process basically has no shrinkage, the calcination process does not produce too many pores, the impregnation process is not required, the production cost is effectively reduced, the production time is shortened, and the production efficiency is improved. The used binder is fluorinated pitch, and fluorine gas is generated by decomposition in the roasting process to further purify the product, so that a high-purity graphitized product can be obtained without a purification process after graphitization.

Description

Technical Field

[0001] The present invention relates to graphite field technology, in particular to a method for preparing isostatically pressed graphite from discarded graphite electrodes. Background Art

[0002] Isostatically pressed graphite is produced by mixing crushed aggregate with a binder and kneading them at high temperature until the aggregate is evenly coated with the binder to form a paste. The aggregate can be graphite or a graphitizable product, and the binder can be asphalt or resin. The paste is then crushed into small particles of appropriate size, packed into an elastic mold and sealed. The mold is then placed into an isostatic pressing vessel, where isostatic pressing applies uniform forces in all directions to press the paste powder into a green compact. Finally, the green compact undergoes a process of calcination, impregnation, calcination, and graphitization, completely converting the aggregate and binder into a graphite product, resulting in isostatically pressed graphite.

[0003] Isostatically pressed graphite boasts high density, high purity, high strength, excellent electrical and thermal conductivity, high temperature resistance, corrosion resistance, and thermal vibration resistance. Its products have a wide range of applications, including nuclear energy, semiconductors, EDM, and glass bending. However, during use, isostatically pressed graphite products inevitably become damaged or replaced, resulting in waste. While these waste products may appear damaged, they still possess the excellent properties of isostatic graphite. Recycling them not only saves costs but also ensures product performance. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies in the prior art, and its main purpose is to provide a method for preparing isostatic graphite from discarded graphite electrodes. The method uses discarded graphite electrodes as raw materials, purifies the raw materials first, then uses fluorinated asphalt as a binder, and subsequently purifies the product again during the roasting and graphitization stages to obtain high-purity isostatic graphite.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing isostatically pressed graphite from discarded graphite electrodes comprises the following steps:

[0007] (1) placing the waste graphite electrode in purified water and cleaning it with the aid of an ultrasonic instrument for 10-30 min, then drying it in a muffle furnace to obtain the cleaned waste graphite electrode;

[0008] (2) placing the cleaned waste graphite electrode obtained in step (1) into a purification furnace, heating it and continuously introducing a strong oxidizing gas, the heating temperature being 2000° C. and the heating time being 1-4 h, to obtain a purified waste graphite electrode;

[0009] (3) placing the purified waste graphite electrode obtained in step (2) into a vertical roller mill for grinding to obtain a raw material powder;

[0010] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0011] (5) grinding the paste obtained in step (4) in a vertical roller mill to obtain a paste powder;

[0012] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0013] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 20-50 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0014] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting, firstly uniformly heating the temperature to 280-320°C and keeping the temperature for 5-20h, then uniformly heating the temperature to 600-630°C and keeping the temperature for 5-20h, then uniformly heating the temperature to 1000-1150°C and keeping the temperature for 10-25h, and finally uniformly cooling the temperature to room temperature to obtain an isostatically pressed graphite roasted body;

[0015] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0016] As a preferred solution, in step (1), the drying temperature is 250° C. and the drying time is 3-6 hours.

[0017] As a preferred solution, the waste graphite electrode in step (1) is an EDM waste graphite electrode.

[0018] As a preferred embodiment, the strong oxidizing gas in step (2) is chlorine.

[0019] As a preferred solution, the particle size of the raw material powder in step (3) is 20-30 μm.

[0020] As a preferred solution, the particle size of the paste powder in step (5) is 20-35 μm.

[0021] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that:

[0022] The use of waste graphite negative electrodes as raw materials not only reduces production costs, but also the waste graphite negative electrodes themselves have good performance. In addition, the waste graphite negative electrodes have a high degree of graphitization, there is basically no shrinkage during the roasting process, the roasting process does not produce excessive pores, and no impregnation process is required, which effectively reduces production costs and shortens production time. In addition, the binder used is fluorinated asphalt, which decomposes during the roasting process to produce fluorine gas for further purification of the product, so that a high-purity graphitized product can be obtained without the need for another purification process after graphitization.

[0023] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below with reference to specific embodiments. DETAILED DESCRIPTION

[0024] The present invention discloses a method for preparing isostatically pressed graphite from discarded graphite electrodes, which comprises the following steps:

[0025] (1) The EDM waste graphite electrode is placed in purified water and cleaned with an ultrasonic instrument for 10-30 minutes, and then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature is 250°C and the drying time is 3-6 hours.

[0026] (2) placing the cleaned waste graphite electrode obtained in step (1) into a purification furnace, heating it and continuously introducing a strong oxidizing gas, the heating temperature being 2000° C. and the heating time being 1-4 hours, to obtain a purified waste graphite electrode; the strong oxidizing gas being chlorine.

[0027] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0028] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0029] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0030] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0031] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 20-50 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0032] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting, firstly uniformly heating the temperature to 280-320°C and keeping it warm for 5-20h, then uniformly heating the temperature to 600-630°C and keeping it warm for 5-20h, then uniformly heating the temperature to 1000-1150°C and keeping it warm for 10-25h, and finally uniformly cooling the temperature to room temperature to obtain an isostatically pressed graphite roasted body.

[0033] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0034] The following describes the details in conjunction with multiple embodiments.

[0035] Example 1

[0036] (1) The EDM waste graphite electrode was placed in purified water and cleaned with an ultrasonic instrument for 10 minutes, and then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature was 250°C and the drying time was 6 hours.

[0037] (2) The cleaned waste graphite electrode obtained in step (1) is placed in a purification furnace and heated while continuously introducing a strong oxidizing gas at a heating temperature of 2000° C. for 2 hours to obtain a purified waste graphite electrode; the strong oxidizing gas is chlorine.

[0038] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0039] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0040] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0041] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0042] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 30 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0043] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting. The temperature is first raised to 280°C at a uniform rate and kept at this temperature for 20 hours. The temperature is then raised to 620°C at a uniform rate and kept at this temperature for 10 hours. The temperature is then raised to 1050°C at a uniform rate and kept at this temperature for 15 hours. The temperature is then lowered to room temperature at a uniform rate to obtain an isostatically pressed graphite roasted body.

[0044] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0045] Example 2

[0046] (1) The EDM waste graphite electrode was placed in purified water and cleaned with an ultrasonic instrument for 30 minutes. It was then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature was 250°C and the drying time was 3 hours.

[0047] (2) The cleaned waste graphite electrode obtained in step (1) is placed in a purification furnace and heated while continuously introducing a strong oxidizing gas at a heating temperature of 2000° C. for 2 hours to obtain a purified waste graphite electrode; the strong oxidizing gas is chlorine.

[0048] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0049] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0050] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0051] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0052] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 40 minutes, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0053] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting. The temperature is first raised to 320°C at a uniform rate and kept at this temperature for 5 hours. The temperature is then raised to 610°C at a uniform rate and kept at this temperature for 18 hours. The temperature is then raised to 1000°C at a uniform rate and kept at this temperature for 175 hours. The temperature is then lowered to room temperature at a uniform rate to obtain an isostatically pressed graphite roasted body.

[0054] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0055] Example 3

[0056] (1) The EDM waste graphite electrode was placed in purified water and cleaned with an ultrasonic instrument for 20 minutes, and then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature was 250°C and the drying time was 6 hours.

[0057] (2) The cleaned waste graphite electrode obtained in step (1) is placed in a purification furnace and heated while continuously introducing a strong oxidizing gas at a heating temperature of 2000° C. for 1 hour to obtain a purified waste graphite electrode; the strong oxidizing gas is chlorine.

[0058] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0059] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0060] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0061] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0062] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 50 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0063] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting. The temperature is first raised to 300°C at a uniform rate and kept at this temperature for 16 hours. The temperature is then raised to 600°C at a uniform rate and kept at this temperature for 20 hours. The temperature is then raised to 1150°C at a uniform rate and kept at this temperature for 17 hours. The temperature is then lowered to room temperature at a uniform rate to obtain an isostatically pressed graphite roasted body.

[0064] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0065] Example 4

[0066] (1) The EDM waste graphite electrode was placed in purified water and cleaned with an ultrasonic instrument for 15 minutes, and then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature was 250°C and the drying time was 4 hours.

[0067] (2) The cleaned waste graphite electrode obtained in step (1) is placed in a purification furnace and heated while continuously introducing a strong oxidizing gas at a heating temperature of 2000° C. for 4 hours to obtain a purified waste graphite electrode; the strong oxidizing gas is chlorine.

[0068] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0069] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0070] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0071] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0072] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 20 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0073] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting. The temperature is first raised to 290°C at a uniform rate and kept at this temperature for 8 hours. The temperature is then raised to 630°C at a uniform rate and kept at this temperature for 5 hours. The temperature is then raised to 1150°C at a uniform rate and kept at this temperature for 25 hours. The temperature is then lowered to room temperature at a uniform rate to obtain an isostatically pressed graphite roasted body.

[0074] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0075] Example 5

[0076] (1) The EDM waste graphite electrode was placed in purified water and cleaned with an ultrasonic instrument for 255 minutes. It was then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature was 250°C and the drying time was 4 hours.

[0077] (2) The cleaned waste graphite electrode obtained in step (1) is placed in a purification furnace and heated while continuously introducing a strong oxidizing gas at a heating temperature of 2000° C. for 1 hour to obtain a purified waste graphite electrode; the strong oxidizing gas is chlorine.

[0078] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0079] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0080] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0081] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0082] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 20-50 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0083] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting. The temperature is first raised to 310°C at a uniform rate and kept at this temperature for 12 hours. The temperature is then raised to 625°C at a uniform rate and kept at this temperature for 11 hours. The temperature is then raised to 1000°C at a uniform rate and kept at this temperature for 20 hours. The temperature is then lowered to room temperature at a uniform rate to obtain an isostatically pressed graphite roasted body.

[0084] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0085] Example 6

[0086] (1) The EDM waste graphite electrode was placed in purified water and cleaned with an ultrasonic instrument for 8 minutes, and then placed in a muffle furnace for drying to obtain the cleaned waste graphite electrode; the drying temperature was 250°C and the drying time was 4.5 hours.

[0087] (2) placing the cleaned waste graphite electrode obtained in step (1) into a purification furnace, heating it and continuously introducing a strong oxidizing gas, the heating temperature being 2000° C. and the heating time being 2.5 h, to obtain a purified waste graphite electrode; the strong oxidizing gas being chlorine.

[0088] (3) The purified waste graphite electrode obtained in step (2) is placed in a vertical roller mill for grinding to obtain a raw material powder; the raw material powder has a particle size of 20-30 μm.

[0089] (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste;

[0090] (5) The paste obtained in step (4) is put into a vertical roller mill for grinding to obtain a paste powder; the paste powder has a particle size of 20-35 μm.

[0091] (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body;

[0092] (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 20 min, and then releasing the pressure to obtain an isostatically pressed graphite green body;

[0093] (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting, firstly uniformly heating to 280°C and keeping warm for 16 hours, then uniformly heating to 620°C and keeping warm for 8 hours, then uniformly heating to 1150°C and keeping warm for 16 hours, and finally uniformly cooling to room temperature to obtain an isostatically pressed graphite roasted body.

[0094] (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

[0095] Performance tests were conducted on the above multiple embodiments, and the test results are shown in Table 1.

[0096]

[0097] Table 1

[0098] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing isostatic graphite from discarded graphite electrodes, characterized in that: The following steps are included: (1) placing the waste graphite electrode in purified water and cleaning it with the aid of an ultrasonic instrument for 10-30 min, then drying it in a muffle furnace to obtain the cleaned waste graphite electrode; (2) placing the cleaned waste graphite electrode obtained in step (1) into a purification furnace, heating it and continuously introducing a strong oxidizing gas, the heating temperature being 2000° C. and the heating time being 1-4 h, to obtain a purified waste graphite electrode; (3) placing the purified waste graphite electrode obtained in step (2) into a vertical roller mill for grinding to obtain a raw material powder; (4) putting the raw material powder obtained in step (3) and fluorinated asphalt into a heating kneader for kneading so that the surface of the raw material powder is evenly coated with a layer of fluorinated asphalt, and then placing it in a cooling layer, and accelerating the cooling by water cooling to a temperature less than 50° C. to obtain a paste; (5) grinding the paste obtained in step (4) in a vertical roller mill to obtain a paste powder; (6) filling the paste powder obtained in step (5) into a rubber mold, compacting it by high-frequency vibration, sealing and vacuuming it to remove the residual air inside the product, and obtaining a preformed isostatically pressed graphite green body; (7) placing the preformed isostatically pressed graphite green body obtained in step (6) into an isostatic pressing device, applying a pressure of 130 MPa and maintaining it for 20-50 min, and then releasing the pressure to obtain an isostatically pressed graphite green body; (8) The isostatically pressed graphite green body obtained in step (7) is placed in a roasting furnace for roasting, firstly uniformly heating the temperature to 280-320°C and keeping the temperature for 5-20h, then uniformly heating the temperature to 600-630°C and keeping the temperature for 5-20h, then uniformly heating the temperature to 1000-1150°C and keeping the temperature for 10-25h, and finally uniformly cooling the temperature to room temperature to obtain an isostatically pressed graphite roasted body; (9) placing the isostatically pressed graphite calcined body obtained in step (8) in a graphitization furnace for graphitization treatment to obtain isostatically pressed graphite.

2. The method for preparing isostatically pressed graphite from waste graphite electrodes according to claim 1, wherein: In the step (1), the drying temperature is 250° C. and the drying time is 3-6 hours.

3. The method for preparing isostatically pressed graphite from waste graphite electrodes according to claim 1, wherein: The waste graphite electrode in the step (1) is an EDM waste graphite electrode.

4. The method for preparing isostatically pressed graphite from waste graphite electrodes according to claim 1, wherein: The strong oxidizing gas in step (2) is chlorine.

5. The method for preparing isostatically pressed graphite from waste graphite electrodes according to claim 1, wherein: The particle size of the raw material powder in step (3) is 20-30 μm.

6. The method for preparing isostatically pressed graphite from waste graphite electrodes according to claim 1, wherein: The particle size of the paste powder in step (5) is 20-35 μm.

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