Graphitization treatment method for calcined petroleum coke

Abstract

The present invention provides a graphitization treatment method for calcined petroleum coke. The calcined petroleum coke is obtained by distilling and thermally cracking crude oil. The graphitization treatment method comprises: step S1, pelletizing calcined petroleum coke to obtain a petroleum coke cathode; and step S2, subjecting the petroleum coke cathode and an anode to molten salt electrolysis, so as to obtain graphitized petroleum coke. In the present invention, by means of a molten salt electrolysis graphitization method, the calcined petroleum coke having a low graphitization degree is converted into a carbonaceous material having a high graphitization degree, namely graphitized petroleum coke. Compared with conventional graphitization methods, using an electrochemical method can effectively lower the graphitization temperature, thereby reducing the energy consumption and cost of graphitization.

Description

Graphitization treatment method for calcined petroleum coke

[0001] This application claims priority to Chinese Patent Application No. 202510126678.2, filed with the Chinese Patent Office on January 27, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of graphitization technology, and more specifically, to a method for graphitizing calcined petroleum coke. Background Technology

[0003] In the aluminum electrolysis industry, calcined petroleum coke serves as a key raw material for prebaked anodes and graphitized cathode carbon blocks, and its degree of graphitization directly affects the efficiency and production cost of aluminum electrolysis. Graphitization is an effective way to alter the structure of carbonaceous materials, giving them properties such as high-temperature resistance, electrical conductivity, and chemical stability. Traditional graphitization processes require high temperatures (typically close to 3000℃), which not only consumes a large amount of electrical energy but also creates hazardous production conditions and generates significant amounts of pollutants.

[0004] Currently, methods for improving graphitization mainly include catalytic graphitization and high-temperature, high-pressure (HTHP) methods. However, catalytic graphitization uses a large amount of catalyst, which is difficult to remove from graphite; HTHP is difficult to achieve graphitization of porous, disordered-layer carbonaceous materials. The main problems currently facing the graphitization process of petroleum coke after aluminum electrolysis include high energy consumption and cost, severe environmental pollution, large fluctuations in raw material quality, significant technological limitations, and increased resource consumption. These problems not only lead to high production costs and severe environmental pollution but also affect the quality of the final product. Therefore, it is necessary to develop a new graphitization technology. Summary of the Invention

[0005] The main objective of this invention is to provide a graphitization treatment method for calcined petroleum coke, in order to solve the problems of high energy consumption and cost, significant environmental pollution, and high requirements for raw materials in the prior art of graphitization of calcined petroleum coke.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for graphitizing calcined petroleum coke is provided, wherein the calcined petroleum coke is obtained from crude oil through distillation and thermal cracking. The graphitization method includes: step S1, pelletizing the calcined petroleum coke to obtain a petroleum coke cathode; and step S2, electrolyzing the petroleum coke cathode and anode with molten salt to obtain graphitized petroleum coke.

[0007] Furthermore, by mass percentage, the calcined petroleum coke comprises: 90–93% carbon, 0.5–1% oxygen, 1–4% sulfur, 0.5–1% nitrogen, and the balance being other impurity elements; and / or, the graphitization degree of the graphitized petroleum coke is 40–65%.

[0008] Furthermore, step S1 above also includes: step S11, grinding the calcined petroleum coke to obtain petroleum coke powder; step S12, granulating the petroleum coke powder by spray drying to obtain petroleum coke microspheres; and step S13, coating the petroleum coke microspheres with a current collector to obtain a petroleum coke cathode.

[0009] Furthermore, the particle size of the petroleum coke powder is 1–100 nm; and / or, the droplet diameter of the spray-dried material is 20–100 μm; and / or, the spray-drying time is 5–10 s; and / or, the diameter of the petroleum coke microspheres is 5–10 μm; the current collector is selected from any one or more of metal mesh, metal foam, graphite paper, graphite mesh, and graphite grid.

[0010] Furthermore, step S2 above also includes sequentially removing moisture from the molten salt and pre-electrolyzing it to obtain the treated molten salt.

[0011] Furthermore, the molten salt was vacuumed at 180–240°C for 16–48 hours to remove moisture.

[0012] Furthermore, the molten salt after moisture removal is pre-electrolyzed after being heated to 900–950°C under an argon atmosphere; and / or, the voltage of the pre-electrolysis is 1.5–2V, and / or, the pre-electrolysis time is 1.5–3h.

[0013] Furthermore, the molten salt is selected from eutectic molten salt and / or fluoride, wherein the eutectic molten salt is selected from any one or more of CaCl2-LiCl, CaCl2-NaCl, CaCl2-BaCl2 and CaCl2-KCl, and the fluoride is selected from any one or more of NaF, CaF2, BaF2 and KF.

[0014] Furthermore, step S2 also includes: step S21, placing the petroleum coke cathode and anode in the treated molten salt for molten salt electrolysis in an inert atmosphere to obtain electrolyzed petroleum coke; and step S22, sequentially washing, acid washing and drying the electrolyzed petroleum coke to obtain graphitized petroleum coke.

[0015] Furthermore, the inert atmosphere is argon or nitrogen; and / or, the anode is graphite; and / or, the temperature of molten salt electrolysis is 850–980°C; and / or, the voltage of molten salt electrolysis is 2.6–3.1V; and / or, the time of molten salt electrolysis is 2–10h; and / or, ultrasonic-assisted distilled water washing is used; and / or, acid washing is performed using an acid solution, the acid solution being a hydrochloric acid solution with a mass concentration of 1–10%; and / or, the drying temperature is 70–80°C.

[0016] By applying the technical solution of this invention, this application transforms low-graphitized calcined petroleum coke into high-graphitized carbonaceous material graphitized petroleum coke through molten salt electrolytic graphitization. Compared with traditional graphitization methods, the electrochemical method can effectively reduce the graphitization temperature, thereby reducing the energy consumption and cost of graphitization. Specifically, in step S1, the calcined petroleum coke undergoes pelletizing treatment, which can effectively improve the structural stability of the calcined petroleum coke and its conductivity with the electrolyte molten salt. Pelletizing treatment involves shaping the raw material into spherical materials with a certain shape and strength. In step S2, during electrolysis, the molten salt not only transmits current and provides the environment for the electrolytic reaction, but also promotes the orderly arrangement of carbon atoms and the formation of graphite structures in the calcined petroleum coke through its unique ionic effects and chemical properties. Specifically, the molten salt electrolysis method can effectively remove gaseous elemental impurities (such as oxygen, sulfur, and nitrogen) from the petroleum coke cathode, as well as a large amount of sulfur. Simultaneously, the removed sulfur ions form elemental sulfur on the anode surface, thereby achieving efficient recovery and utilization of sulfur resources and reducing anode consumption. Furthermore, the processing method described in this application has low requirements for the quality of raw materials and is environmentally friendly. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 shows the XRD pattern of graphitized petroleum coke in Embodiment 1 of this application. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] As analyzed in the background section of this application, the existing technology has problems such as high energy consumption and cost of graphitization of calcined petroleum coke, significant environmental pollution, and high requirements for raw materials. In order to solve the above problems, this application provides a method for graphitization treatment of calcined petroleum coke.

[0021] In a typical embodiment of this application, a method for graphitizing calcined petroleum coke is provided. The calcined petroleum coke is obtained from crude oil through distillation and thermal cracking. The graphitization method includes: step S1, pelletizing the calcined petroleum coke to obtain a petroleum coke cathode; and step S2, electrolyzing the petroleum coke cathode and anode with molten salt to obtain graphitized petroleum coke.

[0022] This application utilizes a molten salt electrolytic graphitization method to convert low-graphitization calcined petroleum coke into highly graphitized carbonaceous material, graphitized petroleum coke. Compared to traditional graphitization methods, the electrochemical approach effectively lowers the graphitization temperature, thereby reducing energy consumption and cost. Specifically, in step S1, the calcined petroleum coke undergoes a pelletizing process, which effectively improves its structural stability and conductivity with the molten salt electrolyte. The pelletizing process involves shaping the raw material into spherical materials with a specific shape and strength. In step S2, during electrolysis, the molten salt not only conducts current and provides the environment for the electrolytic reaction but also promotes the ordered arrangement of carbon atoms and the formation of graphite structures in the calcined petroleum coke through its unique ionic effects and chemical properties. Specifically, the molten salt electrolysis method can effectively remove gaseous elemental impurities (such as oxygen, sulfur, and nitrogen) from the petroleum coke cathode, as well as a large amount of sulfur. Simultaneously, the removed sulfur ions form elemental sulfur on the anode surface, thereby achieving efficient recovery and utilization of sulfur resources and reducing anode consumption. Furthermore, the processing method described in this application has low requirements for the quality of raw materials and is environmentally friendly.

[0023] In one embodiment of this application, the calcined petroleum coke comprises, by mass percentage: 90-93% carbon, 0.5-1% oxygen, 1-4% sulfur, 0.5-1% nitrogen, and the balance being other impurity elements; and / or, the graphitization degree of the graphitized petroleum coke is 40-65%, preferably 52-65%, and more preferably 55.3-64.8%.

[0024] Calcined petroleum coke is the main raw material for making carbon electrodes for aluminum electrolysis in the aluminum electrolysis industry. It is usually obtained by separating light and heavy oil from crude oil through distillation and then converting it into heavy oil through thermal cracking.

[0025] Calcinated petroleum coke containing the aforementioned elements is preferred, as it facilitates better molten salt electrolysis, thereby increasing the degree of graphitization to the aforementioned range.

[0026] In one embodiment of this application, step S1 further includes: step S11, grinding the calcined petroleum coke to obtain petroleum coke powder; step S12, granulating the petroleum coke powder by spray drying to obtain petroleum coke microspheres; and step S13, coating the petroleum coke microspheres with a current collector to obtain a petroleum coke cathode.

[0027] Grinding the calcined petroleum coke is preferred, as it increases the contact area with the electrolyte, thus improving subsequent pelletizing processing. Spray drying is also preferred for pelletizing the petroleum coke powder, further enhancing the structural stability of the calcined petroleum coke and its contact area with the electrolyte, thereby improving conductivity. Encapsulating the petroleum coke microspheres with a current collector is preferred, as it strengthens the conductive connections between the microspheres, further reducing cell pressure.

[0028] In one embodiment of this application, the particle size of the petroleum coke powder is 1-100 nm; and / or, the droplet diameter of the spray-dried material is 20-100 μm; and / or, the spray-drying time is 5-10 s; and / or, the diameter of the petroleum coke microspheres is 5-10 μm; the current collector is selected from any one or more of metal mesh, metal foam, graphite paper, graphite mesh and graphite grid.

[0029] Preferably, the particle size of the petroleum coke powder is within the above-mentioned range, which helps to enhance its contact area with the electrolyte and its reactivity. Preferably, the droplet diameter and time of spray drying, as well as the diameter of the petroleum coke microspheres, are within the above-mentioned ranges, which helps to give the petroleum coke microspheres a good specific surface area and pore structure, thereby facilitating the diffusion of reactants and the release of products. Preferably, the type of current collector is within the above-mentioned range, which helps to better perform molten salt electrolysis.

[0030] In order to improve the conductivity of the electrolyte and reduce the temperature of molten salt electrolysis, in one embodiment of this application, the above step S2 further includes removing moisture and pre-electrolyzing the molten salt in sequence to obtain the treated molten salt.

[0031] In one embodiment of this application, molten salt is dehydrated by vacuuming at 180–240°C in a vacuum environment for 16–48 hours.

[0032] Using the above-mentioned vacuuming method and vacuuming time within the above-mentioned range is preferred, as it helps to effectively remove moisture from the molten salt.

[0033] In one embodiment of this application, the molten salt after moisture removal is pre-electrolyzed after being heated to 900-950°C under an argon atmosphere; and / or, the voltage of the pre-electrolysis is 1.5-2V, and / or, the pre-electrolysis time is 1.5-3h.

[0034] Preheating before pre-electrolysis and controlling the voltage and time of pre-electrolysis within the above-mentioned ranges help remove impurities from the molten salt, thereby helping to provide a more favorable electrolytic environment for graphitization.

[0035] In one embodiment of this application, the molten salt is selected from eutectic molten salt and / or fluoride. The eutectic molten salt is selected from any one or more of CaCl2-LiCl, CaCl2-NaCl, CaCl2-BaCl2 and CaCl2-KCl, and the fluoride is selected from any one or more of NaF, CaF2, BaF2 and KF.

[0036] The above-mentioned types of molten salts are preferred because they are easily soluble in water, and their electrolysis products are easier to remove, which helps to obtain graphitized petroleum coke with higher purity.

[0037] In one embodiment of this application, step S2 further includes: step S21, placing the petroleum coke cathode and anode in the treated molten salt for molten salt electrolysis in an inert atmosphere to obtain electrolyzed petroleum coke; and step S22, sequentially washing, acid washing and drying the electrolyzed petroleum coke to obtain graphitized petroleum coke.

[0038] Preferably, the petroleum coke cathode and anode are placed in treated molten salt for molten salt electrolysis. The treated molten salt helps to conduct current and provides an environment conducive to the electrolytic reaction, thereby promoting the ordered arrangement of carbon atoms and the formation of graphite structures in the petroleum coke cathode. Furthermore, the treated molten salt can be used continuously without the need to replace the electrolyte each time, which helps to reduce costs. Preferably, the petroleum coke after electrolysis is washed with water and acid to help remove impurities, thereby improving the purity of the graphitized petroleum coke.

[0039] In one embodiment of this application, the inert atmosphere is argon or nitrogen; and / or, the anode is graphite; and / or, the temperature of molten salt electrolysis is 850–980°C; and / or, the voltage of molten salt electrolysis is 2.6–3.1V; and / or, the time of molten salt electrolysis is 2–10h; and / or, ultrasonic-assisted distilled water washing is used; and / or, acid washing is performed using an acid solution, the acid solution being a hydrochloric acid solution with a mass concentration of 1–10%; and / or, the drying temperature is 70–80°C.

[0040] Preferably controlling the temperature, voltage, and time of molten salt electrolysis within the aforementioned ranges helps promote the ordered arrangement of carbon atoms and the formation of graphite structures in the petroleum coke cathode, thereby increasing the degree of graphitization of the graphitized petroleum coke. Preferably employing ultrasonic-assisted distilled water washing helps to better remove molten salt and other impurities. Preferably using the aforementioned acid solution for acid washing helps to remove metal ion contamination from the electrolyzed petroleum coke. Preferably performing drying under vacuum and controlling the drying temperature within the aforementioned range helps to reduce structural changes in the graphitized petroleum coke material caused by high temperatures.

[0041] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0042] Example 1

[0043] By mass percentage, calcined petroleum coke comprises: 92% carbon, 0.8% oxygen, 2.5% sulfur, 0.6% nitrogen, with the balance being other impurities. The calcined petroleum coke is ground to obtain petroleum coke powder with a particle size of 45 nm. The petroleum coke powder is then pelletized using spray drying to obtain petroleum coke microspheres with a diameter of 8 μm. These microspheres are subsequently wrapped with graphite paper current collectors to obtain petroleum coke cathodes. The droplet diameter during spray drying is 60 μm, and the spray drying time is 8 s.

[0044] 180g of anhydrous CaCl2-LiCl eutectic molten salt (Molar ratio of CaCl2 to LiCl: 0.65:0.35) was placed in an alumina crucible and vacuumed at 200℃ for 24h to remove moisture. Then, under an argon atmosphere, the temperature was raised to 920℃ and pre-electrolyzed at 1.8V for 2h to obtain the treated molten salt. In an argon atmosphere, a petroleum coke cathode and a graphite anode were placed in the treated molten salt, and molten salt electrolysis at a constant voltage of 2.8V was performed at 950℃ for 6h to obtain electrolyzed petroleum coke. The electrolyzed petroleum coke was then washed with ultrasonic-assisted distilled water, acid-washed with a 3% hydrochloric acid solution, and dried under vacuum at 75℃ to obtain graphitized petroleum coke.

[0045] Example 2

[0046] By mass percentage, calcined petroleum coke comprises: 90% carbon, 0.5% oxygen, 1% sulfur, 0.5% nitrogen, and the balance being other impurities. The calcined petroleum coke is ground to obtain petroleum coke powder with a particle size of 1 nm. The petroleum coke powder is then pelletized using spray drying to obtain petroleum coke microspheres with a diameter of 5 μm, which are subsequently placed in… In a graphite frame current collector, a petroleum coke cathode is fabricated by connecting it to a 304 stainless steel rod. The droplet diameter during spray drying is 20 μm, and the spray drying time is 5 s.

[0047] 150g of anhydrous CaCl2-NaCl eutectic molten salt (Molar ratio of CaCl2 to NaCl: 0.7:0.3) was placed in an alumina crucible and vacuumed at 180℃ for 48h to remove moisture. Then, under an argon atmosphere, the temperature was raised to 900℃ and pre-electrolyzed at 1.5V for 3h to obtain the treated molten salt. In an argon atmosphere, a petroleum coke cathode and a graphite anode were placed in the treated molten salt, and molten salt electrolysis was performed at a constant voltage of 2.6V at 850℃ for 10h to obtain electrolyzed petroleum coke. The electrolyzed petroleum coke was then washed with ultrasonic-assisted distilled water, acid-washed with a 1% hydrochloric acid solution, and dried under vacuum at 70℃ to obtain graphitized petroleum coke.

[0048] Example 3

[0049] By mass percentage, calcined petroleum coke comprises: 93% carbon, 1% oxygen, 4% sulfur, 1% nitrogen, with the balance being other impurities. The calcined petroleum coke is ground to obtain petroleum coke powder with a particle size of 100 nm. The petroleum coke powder is then pelletized using spray drying to obtain petroleum coke microspheres with a diameter of 10 μm, which are subsequently placed in… In a graphite frame current collector, a petroleum coke cathode is fabricated by connecting it to a 304 stainless steel rod. The droplet diameter during spray drying is 100 μm, and the spray drying time is 10 s.

[0050] 200g of BaF2 was placed in an alumina crucible and vacuumed at 240℃ for 16 hours to remove moisture. Then, under an argon atmosphere, the temperature was raised to 950℃ and pre-electrolyzed at 2V for 1.5 hours to obtain treated molten salt. In an argon atmosphere, a petroleum coke cathode and a graphite anode were placed in the treated molten salt, and molten salt electrolysis at a constant voltage of 3.1V was performed at 980℃ for 2 hours to obtain electrolyzed petroleum coke. The electrolyzed petroleum coke was then washed with ultrasonic-assisted distilled water, acid-washed with a 10% hydrochloric acid solution, and dried under vacuum at 80℃ to obtain graphitized petroleum coke.

[0051] Example 4

[0052] The difference from Example 1 is that the droplet diameter of the spray drying is 100 μm and the spray drying time is 10 s, finally obtaining graphitized petroleum coke.

[0053] Example 5

[0054] The difference from Example 1 is that the droplet diameter of the spray drying is 150 μm and the spray drying time is 3 s, finally obtaining graphitized petroleum coke.

[0055] Example 6

[0056] The difference from Example 1 is that the temperature of molten salt electrolysis is 980°C, and graphitized petroleum coke is finally obtained.

[0057] Example 7

[0058] The difference from Example 1 is that the temperature of molten salt electrolysis is 820°C, and graphitized petroleum coke is finally obtained.

[0059] Example 8

[0060] The difference from Example 1 is that the voltage of molten salt electrolysis is 2.6V and the electrolysis time is 4h, ultimately yielding graphitized petroleum coke.

[0061] Example 9

[0062] The difference from Example 1 is that the voltage of molten salt electrolysis is 3.5V and the electrolysis time is 1h, ultimately yielding graphitized petroleum coke.

[0063] Comparative Example 1

[0064] The calcined petroleum coke was placed in an Atchison graphitization furnace and heated at 3000℃ for 48 hours to obtain graphitized petroleum coke.

[0065] Comparative Example 2

[0066] The difference from Example 1 is that the calcined petroleum coke is ground and then wrapped with a graphite paper current collector to obtain a petroleum coke cathode, and finally graphitized petroleum coke is obtained.

[0067] Test methods

[0068] The graphitized petroleum coke of the above embodiments and comparative examples were subjected to performance tests, and the test results are shown in Table 1.

[0069] Table 1

[0070] Figure 1 is the XRD pattern of graphitized petroleum coke in Example 1. As can be seen from Figure 1, the diffraction angle corresponding to the (002) crystal plane of the calcined petroleum coke after molten salt electrolysis is 26.33°. According to the Mering-Maire formula (Franklin formula) for calculating the degree of graphitization, the degree of graphitization of the calcined petroleum coke under this electrolysis condition is 64.2%.

[0071] Compared to the high-temperature graphitization method of Comparative Example 1, the embodiments of this application can still achieve a high degree of graphitization at a lower temperature. Therefore, this application can reduce the energy consumption and cost of graphitizing calcined petroleum coke while maintaining the desired degree of graphitization.

[0072] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0073] This application utilizes a molten salt electrolytic graphitization method to convert low-graphitization calcined petroleum coke into highly graphitized carbonaceous material, graphitized petroleum coke. Compared to traditional graphitization methods, the electrochemical approach effectively lowers the graphitization temperature, thereby reducing energy consumption and cost. Specifically, in step S1, the calcined petroleum coke undergoes a pelletizing process, which effectively improves its structural stability and conductivity with the molten salt electrolyte. The pelletizing process involves shaping the raw material into spherical materials with a specific shape and strength. In step S2, during electrolysis, the molten salt not only conducts current and provides the environment for the electrolytic reaction but also promotes the ordered arrangement of carbon atoms and the formation of graphite structures in the calcined petroleum coke through its unique ionic effects and chemical properties. Specifically, the molten salt electrolysis method can effectively remove gaseous elemental impurities (such as oxygen, sulfur, and nitrogen) from the petroleum coke cathode, as well as a large amount of sulfur. Simultaneously, the removed sulfur ions form elemental sulfur on the anode surface, thereby achieving efficient recovery and utilization of sulfur resources and reducing anode consumption. Furthermore, the processing method described in this application has low requirements for the quality of raw materials and is environmentally friendly.

[0074] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. 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 graphitizing calcined petroleum coke, wherein the calcined petroleum coke is obtained from crude oil through distillation and thermal cracking, characterized in that, The graphitization process includes: Step S1, the calcined petroleum coke is subjected to pelletizing treatment to obtain a petroleum coke cathode; and Step S2 involves molten salt electrolysis of the petroleum coke cathode and anode to obtain graphitized petroleum coke.

2. The graphitization treatment method according to claim 1, characterized in that, The calcined petroleum coke comprises, by mass percentage: 90-93% carbon, 0.5-1% oxygen, 1-4% sulfur, 0.5-1% nitrogen, and the balance being other impurity elements; and / or, the graphitized petroleum coke has a graphitization degree of 40-65%.

3. The graphitization treatment method according to claim 1 or 2, characterized in that, Step S1 further includes: Step S11: Grind the calcined petroleum coke to obtain petroleum coke powder; Step S12, the petroleum coke powder is subjected to the pelletizing treatment by spray drying to obtain petroleum coke microspheres; and Step S13: The petroleum coke microspheres are wrapped with a current collector to obtain the petroleum coke cathode.

4. The graphitization treatment method according to claim 3, characterized in that, The petroleum coke powder has a particle size of 1–100 nm; and / or, the droplet diameter of the spray drying is 20–100 μm; and / or, the spray drying time is 5–10 s; and / or, the diameter of the petroleum coke microspheres is 5–10 μm; the current collector is selected from any one or more of metal mesh, metal foam, graphite paper, graphite mesh, and graphite grid.

5. The graphitization treatment method according to claim 1 or 2, characterized in that, Step S2 further includes sequentially removing moisture from the molten salt and pre-electrolyzing it to obtain the treated molten salt.

6. The graphitization treatment method according to claim 5, characterized in that, The molten salt is subjected to dehydration under vacuum conditions at 180–240°C for 16–48 hours.

7. The graphitization treatment method according to claim 5, characterized in that, The molten salt after moisture removal is pre-electrolyzed after being heated to 900-950°C under an argon atmosphere; and / or the voltage of the pre-electrolysis is 1.5-2V, and / or the time of the pre-electrolysis is 1.5-3h.

8. The graphitization treatment method according to claim 5, characterized in that, The molten salt is selected from eutectic molten salts and / or fluorides, wherein the eutectic molten salt is selected from any one or more of CaCl2-LiCl, CaCl2-NaCl, CaCl2-BaCl2 and CaCl2-KCl, and the fluoride is selected from any one or more of NaF, CaF2, BaF2 and KF.

9. The graphitization treatment method according to claim 5, characterized in that, Step S2 further includes: Step S21: In an inert atmosphere, the petroleum coke cathode and the anode are placed in the treated molten salt for molten salt electrolysis to obtain electrolyzed petroleum coke; and Step S22: The electrolyzed petroleum coke is sequentially washed with water, acid-washed, and dried to obtain the graphitized petroleum coke.

10. The graphitization treatment method according to claim 9, characterized in that, The inert atmosphere is argon or nitrogen; and / or, the anode is graphite; and / or, the temperature of the molten salt electrolysis is 850–980°C; and / or, the voltage of the molten salt electrolysis is 2.6–3.1V; and / or, the time of the molten salt electrolysis is 2–10h. And / or, the water washing is performed using ultrasonic-assisted distilled water; and / or, the acid washing is performed using an acid solution, wherein the acid solution is a hydrochloric acid solution with a mass concentration of 1-10%; and / or, the drying temperature is 70-80°C.

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