Preparation process of large-size graphitization furnace head conductive electrode

Abstract

The present application relates to the field of graphite preparation, a preparation process of large-size graphitized furnace head conductive electrode, comprising: mixing, mixing and kneading, vibration forming, baking furnace baking to obtain electrode blank, using series connection type graphitization furnace for graphitization, starting power 2415kW, rising to 2938kW for 6.5 hours, falling to 2455kW for 3 hours, rising to 5306kW for 40 hours, rising to 6595kW for 6.5 hours, rising to 12000kW. The power supply curve of the present application, aiming at large-size graphite electrode, ensures that the internal stress and volatile matter in the graphitization temperature rising process are within the controllable range; aiming at the high sulfur content of sponge coke and projectile coke in the electrode blank formula, the rapid reaction and release of sulfur and sulfur carbon compounds during high temperature heating are controlled, the internal force generated during graphitization is reduced, thereby reducing cracks, preventing the formation of small holes and cracks in the electrode, and improving the density and conductivity.

Description

Technical Field

[0001] This invention relates to the field of graphite preparation, and more particularly to a process for preparing a large-scale graphitized furnace head conductive electrode. Background Technology

[0002] Lengthwise graphitization furnace: This is a resistance furnace that directly passes current through a series of baked products, utilizing the resistance of the products themselves to convert electrical energy into heat energy, thus graphitizing the products. Its basic principle involves placing the baking electrodes horizontally inside the furnace, connecting them in a straight line along their axis, and then fixing them between two conductive electrodes. To reduce heat loss, insulating material is placed around the baking electrodes.

[0003] In internally heated series graphitization furnaces, heating time, temperature rise curve, and final graphitization temperature are crucial factors affecting the final graphitization effect of the calcined product and the furnace's energy consumption. Overall longitudinal cracking of the electrode is a common quality problem encountered in internally heated series graphitization production and a significant factor impacting electrode production costs. One of the main causes of overall longitudinal cracking is an improperly designed power supply and heating curve, which causes the stress changes within the electrode to exceed the product's own expansion limit stress, leading to longitudinal cracking.

[0004] The series-connected graphitized column consists of several calcined products connected in series and tightly pressed together along the longitudinal direction. The end-face contact area is a critical point. During energization, the high resistance at the end-face contact area causes the temperature to rise, making it prone to cracking. Excessive electrode contact area leads to excessive current passing through the center of the electrode, causing the internal thermal expansion force of the product to exceed that of the surface, resulting in longitudinal cracks. To address this, embedding a flexible graphite gasket of appropriate thickness at the connection point between the two calcined products during furnace loading and pressing it tightly can reduce the occurrence of these cracks.

[0005] CN201711421602.4 A method for graphitizing ultra-large-sized graphite products and the same, relating to graphite product processing, specifically using an Acheson graphitization furnace. By adjusting the initial furnace core resistance, changing the loading method of ultra-large-sized graphite products, and adjusting the power rise rate of the power supply curve, the graphitized products exhibit good densification properties, improving the yield. CN201510655607.8 A method for graphitizing fine-particle graphite products using an Acheson graphitization furnace, relating to the field of graphite material manufacturing and processing, significantly reducing the generation of graphitization cracked waste products, improving the yield of the graphitization process, reducing graphitization production costs, and increasing the company's economic benefits. CN201410368599.4 A 348mm diameter graphite electrode and its manufacturing method, using an Acheson graphitization furnace, successfully solving the problem of easy cracking and low yield of small-particle powder multi-electrodes during calcination and graphitization heat treatment.

[0006] CN201110182804.4 A 318mm diameter ultra-high power graphite electrode connector and its production method, solving the problem that coal-based needle coke cannot produce large-size ultra-high power graphite electrode connectors due to its poor main physicochemical properties, thus realizing the localization of the main raw materials for ultra-high power graphite electrode connectors. CN202011135511.6 A preparation process for a φ700mm ultra-high power graphite electrode, using domestically produced Jingyang needle coke, calcined petroleum coke, and graphite fragments as aggregates, and medium-temperature modified coal tar pitch with a softening point of 95-105℃ and a coking value ≥58% as a binder, to manufacture a φ700mm ultra-high power graphite electrode. Summary of the Invention

[0007] The purpose of this invention is to provide a process for preparing conductive electrodes for large-scale graphitized furnace heads. This process reduces the occurrence of cracks in conductive electrodes for large-scale graphitized furnace heads during low-cost industrial production. By optimizing the power delivery curve accordingly, the effect and quality of graphitization are ensured.

[0008] The present invention adopts the following technical solution: A process for preparing conductive electrodes for large-scale graphitization furnace heads, employing a series-connected graphitization furnace for graphitization. The power transmission curve during power transmission is as follows: Initial power: 2350-2450kW; In the first stage, the power was increased to 2900-3000kW, taking 6-6.5 hours; In the second stage, the power is reduced to 2400-2500kW, and the time taken is 3-3.5 hours; In the third stage, the power is increased to 5250-5350kW, and the time is 39-41 hours. In the fourth stage, the power is increased to 6550-6650kW, taking 6-6.5 hours; In the fifth stage, the power increased to 12000kW, taking 3.479 to 3.518 hours; In the sixth stage, maintain the power at 12000kW for 2 to 2.5 hours.

[0009] Preferably, a linear series-connected graphitization furnace is used for graphitization. The power delivery curves for the first, second, third, and fourth stages are all linear; the power delivery curve for the fifth stage is as follows: Y=Z+154*X+511.75*X*X-32.72*X*X*X Y represents the power transmitted; X represents time; and Z represents the power transmitted at the end of the fourth stage.

[0010] As a preferred option, the conductive electrode of the large-size graphitization furnace head has a length of 3000-5000 mm and a diameter of 1400-2000 mm.

[0011] As a preferred option, a linear series-connected graphitization furnace is used for graphitization, and the power supply curve during power supply is as follows: Initial power: 2415kW; In the first stage, the power was increased to 2920-2960kW, taking 6.3-6.5 hours; In the second stage, the power is reduced to 2430-2470kW, and the time taken is 3-3.2 hours; In the third stage, the power is increased to 5280-5330kW, and the time taken is 39.5-40.5 hours; In the fourth stage, the power increased to 6595kW, taking 6.3 to 6.5 hours; In the fifth stage, the power was increased to 12000kW, taking 3.5 hours. In the sixth stage, maintain a power of 12000kW for 2.4 to 2.5 hours.

[0012] In the fifth stage, the power transmission curve is: Y = 6595 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time.

[0013] As a preferred option, the process for preparing conductive electrodes for large-scale graphitization furnace heads includes the following steps in the graphitization process of a series-connected graphitization furnace: furnace body preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply.

[0014] Preferably, the insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

[0015] Preferably, the electrode blank is prepared from the following parts by weight of raw materials: 6-10 parts of petroleum coke with a particle size of 6-9 mm; 42-49 parts of petroleum coke with a particle size of 1-6 mm; 6-10 parts of petroleum coke with a particle size of 0.5-1mm; 34-41 parts of petroleum coke with a particle size of less than 0.5 mm; 17-23 parts of coal tar pitch.

[0016] Preferably, the electrode blank is prepared from the following parts by weight of raw materials: 6-10 parts of sponge coke with a particle size of 6-9 mm; 42-49 parts of bullet coke with a particle size of 1-6 mm; 6-10 parts of bullet coke with a particle size of 0.5-1mm; 34-41 parts of petroleum coke with a particle size of less than 0.5 mm, consisting of 50% sponge coke and 50% pellet coke; 17-23 parts of coal tar pitch with a softening point of 105℃~115℃.

[0017] Preferably, the electrode blank is prepared by the following steps: ingredient mixing, kneading, vibration molding, and baking in a baking furnace to obtain the electrode blank.

[0018] Preferably, the end faces of the electrode blanks are connected by a flexible graphite ring, the thickness of which is 20mm to 30mm and the ratio of the inner diameter to the outer diameter of which is 5 to 7:10.

[0019] Preferably, the flexible graphite ring has through holes with a diameter of 3-4 mm in a region of 20-30% of the annular width near the inner edge, with an opening rate of 20-30%; the flexible graphite ring has no holes in a region of 15-20% of the annular width near the outer edge; and the remaining regions of the flexible graphite ring have through holes with a diameter of 1.5-2 mm, with an opening rate of 10-15%.

[0020] Compared with existing technologies, the fabrication process of the large-scale graphitized furnace head conductive electrode of this invention has the following advantages: The optimized graphitization power supply curve of this invention is designed for the industrial production of large-size graphite electrodes. It ensures that the internal stress and volatile matter during the graphitization heating process are within a controllable range, reduces the internal forces generated during graphitization, thereby reducing cracks, and ensures uniform temperature distribution, greatly reducing the occurrence of cracks and defects.

[0021] The specific graphitization power supply curve of this invention, for high-sulfur formulation electrode blanks made from sponge coke and pellet coke, controls the excessively rapid reaction and release of sulfur and sulfur-carbon compounds during high-temperature heating, prevents the formation of tiny pores and cracks inside the electrode, improves density and conductivity, and solves the problem of high-yield industrial production of large-size graphitized furnace head conductive electrodes with high sulfur content formulations.

[0022] This invention uses a specially designed flexible graphite gasket to ensure that more current can pass through the electrode surface during the power supply process, thus avoiding cracks caused by excessive temperature difference between the internal and surface of the electrode during power supply. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the power transmission curves in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention.

[0024] Figure 2 The diagram shows the flexible graphite rings in Embodiments 1, 2, and 3 of this invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] Example 1: The process for preparing conductive electrodes for large-scale graphitization furnace heads involves graphitization using a series-connected graphitization furnace, including furnace preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply.

[0027] The power transmission curve during power transmission is as follows: Initial power: 2415kW; In the first stage, the power was linearly increased to 2938kW in 6.5 hours; In the second stage, the power was linearly reduced to 2455kW, taking 3 hours; In the third stage, the power was linearly increased to 5306kW, taking 40 hours; In the fourth stage, the power increased linearly to 6595kW in 6.5 hours; In the fifth stage, the power was increased to 12,000 kW, taking 3.5 hours; In the sixth stage, the power was maintained at 12000kW for 2.5 hours. In the fifth stage, the power transmission curve is: Y = 6595 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time, ranging from 0 to 3.5.

[0028] The insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

[0029] The conductive electrode of the large-size graphitization furnace head has a length of 4800mm and a diameter of 2000mm.

[0030] The electrode blank end faces are connected by flexible graphite rings. The thickness of the flexible graphite rings is 25mm, and the ratio of the inner diameter to the outer diameter of the flexible graphite rings is 5.5:10. Figure 2 As shown, the flexible graphite ring has a 128mm wide annular region 3 near its inner edge with a 3.4mm diameter through hole and an opening rate of 20-30%; the flexible graphite ring has a 78mm wide annular region 1 near its outer edge without holes; the remaining regions 2 of the flexible graphite ring have 1.6mm diameter through holes distributed with an opening rate of 10-15%.

[0031] The electrode blank preparation includes, by mass parts: 6-10 parts of sponge coke with a particle size of 6-9 mm, 42-49 parts of shot coke with a particle size of 1-6 mm, 6-10 parts of shot coke with a particle size of 0.5-1 mm, and 34-41 parts of petroleum coke with a particle size of less than 0.5 mm, each accounting for 50% of the sponge coke and shot coke. The dry materials of sponge coke and shot coke are mixed; 17-23 parts of coal tar pitch are added for kneading; the mixture is vibrated and shaped in a vibration molding device, cooled in a water tank, and then roasted in a roasting furnace.

[0032] Among them, the pellet coke is pretreated by calcining at 1900℃~2200℃ for 5~10 minutes before being crushed; The coal tar pitch has a softening point of 105℃~115℃, a sulfur content of ≤2%, an ash content of ≤0.3%, and a sulfur content of ≤0.3%.

[0033] The billet is preheated to 150°C and placed in a roasting furnace for roasting. A natural gas ring roasting furnace is used, with 8 furnace chambers in the heating state. The highest roasting temperature is 1000°C to 1100°C, and the roasting is carried out for 768 hours under air-isolated conditions. Phase 1: The temperature linearly increased from 150℃ to 230℃ over 96 hours. The second stage: taking 48 hours, the temperature linearly increased from 230℃ to 276℃; The third stage: taking 48 hours, the temperature linearly increased from 276℃ to 324℃; Phase 4: The temperature linearly increased from 324℃ to 431℃ over 96 hours. Fifth stage: The temperature linearly increased from 431℃ to 606℃ over 192 hours; Stage 6: The temperature rose from 606℃ to 1078℃ in 252 hours. The temperature rise curve is: Y=1169.365-3.17*(X+480)+0.00416*(X+480)*(X+480); Y is the temperature; X is the time, ranging from 0 to 252. Phase 7: 732–768 hours, with the temperature maintained at 1078℃.

[0034] Example 2: The process for preparing conductive electrodes for large-scale graphitization furnace heads involves graphitization using a linear series graphitization furnace, including furnace preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply.

[0035] The power transmission curve during power transmission is as follows: Initial power 2350kW; In the first phase, the power was increased to 2900kW, taking 6 hours; In the second stage, the power was reduced to 2400kW, and the time was 3 hours. In the third stage, the power was increased to 5250kW, taking 39 hours; In the fourth stage, the power was increased to 6550kW, taking 6 hours; In the fifth stage, the power was increased to 12,000 kW, taking 3.518 hours; In the sixth stage, maintain a power of 12000kW for 2 hours; In the fifth stage, the power transmission curve is: Y = 6550 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time, ranging from 0 to 3.518.

[0036] The insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

[0037] The conductive electrode of the large-size graphitization furnace head has a length of 3000mm and a diameter of 1400mm.

[0038] The electrode blank end faces are connected by flexible graphite rings, each 20mm thick, with an inner-to-outer diameter ratio of 5:7. For example... Figure 2 As shown, the flexible graphite ring has a 40mm wide annular region 3 near its inner edge with a 3mm diameter through hole, and the opening rate is 20-30%; the flexible graphite ring has a 30mm wide annular region 1 near its outer edge without holes; the remaining regions 2 of the flexible graphite ring have 1.5mm diameter through holes distributed, and the opening rate is 10-15%.

[0039] The preparation of electrode blanks includes, by mass parts: 6-10 parts of sponge coke with a particle size of 6-9 mm, 42-49 parts of shot coke with a particle size of 1-6 mm, 6-10 parts of shot coke with a particle size of 0.5-1 mm, and 34-41 parts of petroleum coke with a particle size of less than 0.5 mm, each accounting for 50% of the sponge coke and shot coke. The dry materials of sponge coke and shot coke are mixed; 17-23 parts of coal tar pitch are added for kneading; the mixture is vibrated and shaped in a vibration molding device, cooled in a water tank, and then roasted in a roasting furnace.

[0040] Among them, the pellet coke is pretreated by calcining at 1900℃~2200℃ for 5~10 minutes before being crushed; The coal tar pitch has a softening point of 105℃~115℃, a sulfur content of ≤2%, an ash content of ≤0.3%, and a sulfur content of ≤0.3%.

[0041] Example 3: The process for preparing conductive electrodes for large-scale graphitization furnace heads involves graphitization using a linear series graphitization furnace, including furnace preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply.

[0042] The power transmission curve during power transmission is as follows: Initial power: 2450kW; In the first phase, the power was increased to 3000kW, taking 6.5 hours; In the second stage, the power was reduced to 2500kW, and the time was 3.5 hours. In the third stage, the power was increased to 5350kW, taking 41 hours; In the fourth stage, the power was increased to 6650kW, taking 6.5 hours; In the fifth stage, the power was increased to 12000kW, taking 3.479 hours. In the sixth stage, the power was maintained at 12000kW for 2.5 hours. In the fifth stage, the power transmission curve is: Y = 6650 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time, ranging from 0 to 3.479.

[0043] The insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

[0044] The conductive electrode of the large-size graphitization furnace head has a length of 5000mm and a diameter of 2000mm.

[0045] The electrode blanks are connected at their end faces by flexible graphite rings. The flexible graphite rings are 30mm thick and have an inner diameter to outer diameter ratio of 5:10. Figure 2 As shown, the flexible graphite ring has a 150mm wide annular region 3 near its inner edge with a 4mm diameter through hole, and the opening rate is 20-30%; the flexible graphite ring has a 100mm wide annular region 1 near its outer edge without holes; the remaining regions 2 of the flexible graphite ring have 2mm diameter through holes distributed, and the opening rate is 10-15%.

[0046] The preparation of electrode blanks includes, by mass parts: 6-10 parts of sponge coke with a particle size of 6-9 mm, 42-49 parts of shot coke with a particle size of 1-6 mm, 6-10 parts of shot coke with a particle size of 0.5-1 mm, and 34-41 parts of petroleum coke with a particle size of less than 0.5 mm, each accounting for 50% of the sponge coke and shot coke. The dry materials of sponge coke and shot coke are mixed; 17-23 parts of coal tar pitch are added for kneading; the mixture is vibrated and shaped in a vibration molding device, cooled in a water tank, and then roasted in a roasting furnace.

[0047] Among them, the pellet coke is pretreated by calcining at 1900℃~2200℃ for 5~10 minutes before being crushed; The coal tar pitch has a softening point of 105℃~115℃, a sulfur content of ≤2%, an ash content of ≤0.3%, and a sulfur content of ≤0.3%.

[0048] Comparative Example 1: The difference from Example 1 is that the power transmission curve in CN201110182804.4 is used: Initial power: 3600kW; In the first stage, the power was linearly increased to 5000kW in 4 hours; In the second stage, the power was linearly reduced to 4200kW, taking 1 hour; In the third stage, the power was linearly increased to 4700kW, taking 1 hour; In the fourth stage, the power was linearly increased to 5500kW, taking 1 hour; In the fifth stage, the power was linearly increased to 8500kW, taking 1 hour; In the sixth stage, the power was linearly increased to 11,000 kW, taking 1 hour; In the seventh stage, the power was linearly increased to 13,000 kW in 1 hour; The eighth stage maintains a power of 13,000 kW for 2 hours.

[0049] Comparative Example 2: The difference from Example 1 is that the power transmission curve during power transmission is as follows: Initial power: 2415kW; In the first stage, the power was linearly increased to 3000kW in 6.5 hours; In the second stage, the power was linearly reduced to 2520kW, taking 3 hours; In the third stage, the power was linearly increased to 6000kW in 40 hours; In the fourth stage, the power increased linearly to 9016kW in 6.5 hours; In the fifth stage, the power was linearly increased to 12000kW in 3.5 hours; In the sixth stage, the power is maintained at 12000kW for 2.5 hours.

[0050] Comparative Example 3: The process for preparing conductive electrodes for large-scale graphitization furnace heads, using a series-connected graphitization furnace for graphitization, including furnace body preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply.

[0051] The power transmission curve during power transmission is as follows: Initial power: 2415kW; In the first stage, the power was linearly increased to 2938kW in 6.5 hours; In the second stage, the power was linearly reduced to 2455kW, taking 3 hours; In the third stage, the power was linearly increased to 5306kW, taking 40 hours; In the fourth stage, the power increased linearly to 6595kW in 6.5 hours; In the fifth stage, the power was increased to 12,000 kW, taking 3.5 hours; In the sixth stage, the power was maintained at 12000kW for 2.5 hours. In the fifth stage, the power transmission curve is: Y = 6595 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time, ranging from 0 to 3.5.

[0052] The insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

[0053] The conductive electrode of the large-size graphitization furnace head has a length of 5000mm and a diameter of 2000mm.

[0054] The electrode blanks are connected by a flexible graphite ring with a thickness of 20 mm and an inner diameter to outer diameter ratio of 6:10.

[0055] Comparative Example 4: The process for preparing conductive electrodes for large-scale graphitization furnace heads, using a series-connected graphitization furnace for graphitization, includes furnace body preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply.

[0056] The power transmission curve during power transmission is as follows: Initial power: 2415kW; In the first stage, the power was linearly increased to 2938kW in 6.5 hours; In the second stage, the power was linearly reduced to 2455kW, taking 3 hours; In the third stage, the power was linearly increased to 5306kW, taking 40 hours; In the fourth stage, the power increased linearly to 6595kW in 6.5 hours; In the fifth stage, the power was increased to 12,000 kW, taking 3.5 hours; In the sixth stage, the power was maintained at 12000kW for 2.5 hours. In the fifth stage, the power transmission curve is: Y = 6595 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time, ranging from 0 to 3.5.

[0057] The insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

[0058] The conductive electrode of the large-size graphitization furnace head has a length of 5000mm and a diameter of 2000mm.

[0059] The electrode blanks are connected at their end faces by a flexible graphite ring. The flexible graphite ring is 25 mm thick and has an inner diameter to outer diameter ratio of 5.5:10. The surface of the flexible graphite ring has through holes with a diameter of 3.4 mm, and the porosity is 20-30%.

[0060] Table 1: Comparison of indicators between Examples 1-3 and Comparative Examples 1-4

[0061] As shown in Table 1, the same electrode blanks were used in Examples 1 to 3, and the power supply curves were adjusted within the range respectively; the main indicators of the graphitized furnace head conductive electrodes obtained were quite similar.

[0062] Comparative Example 1 used a 12-hour power supply curve, but this curve not only failed to effectively complete graphitization, but also resulted in an extremely high rate of crack defects. This was because an optimized power supply curve was not determined for the different formulations and dimensions of the electrode blanks.

[0063] Comparative Example 2 used a power supply curve similar to that of Example 1 for 62 hours. However, this power supply curve did not achieve optimal control in the 1400-1800℃ range. During this process, elements such as oxygen, nitrogen, and sulfur bound in the carbon microcrystalline structure escaped, especially gaseous sulfides, resulting in more micropores and cracks. This affected the main indicators of the conductive electrode of the graphitized furnace head.

[0064] Comparative Example 3 uses a common flexible graphite ring connection, while Comparative Example 4 uses a flexible graphite ring connection with a simple 3.4mm through hole. The remaining steps are the same as in Example 1. Compared to the specific staged perforation-guided flexible graphite ring in Example 1 of this invention, Comparative Example 3 and Comparative Example 4 have a slightly lower ability to guide more current to the electrode surface, resulting in a slightly higher crack rate at the end-face contact area; this affects the conductive electrode of the graphitization furnace head.

Claims

1. A process for preparing a large-scale graphitized furnace head conductive electrode, characterized in that... include: Furnace preparation, laying insulation material, loading electrode blanks, covering with insulation material, and power supply; The electrode blank is a high-sulfur-content electrode blank; The graphitization process is carried out using a series-connected graphitization furnace. The power supply curve during power supply is as follows: Initial power: 2350-2450kW; In the first stage, the power was increased to 2900-3000kW, taking 6-6.5 hours; In the second stage, the power is reduced to 2400-2500kW, and the time taken is 3-3.5 hours; In the third stage, the power is increased to 5250-5350kW, and the time is 39-41 hours. In the fourth stage, the power is increased to 6550-6650kW, taking 6-6.5 hours; In the fifth stage, the power increased to 12000kW, taking 3.479 to 3.518 hours; In the sixth stage, maintain a power of 12000kW for 2 to 2.5 hours; The electrode blank end faces are connected by a flexible graphite ring, the thickness of which is 20mm to 30mm, and the ratio of the inner diameter to the outer diameter of which is 5 to 7:

10. The flexible graphite ring has through holes with a diameter of 3-4 mm in a region of 20-30% of its inner edge, resulting in an opening rate of 20-30%. The flexible graphite ring has no holes in the area of ​​15-20% of its annular width near the outer edge. The remaining area of ​​the flexible graphite ring has through holes with a diameter of 1.5 to 2 mm, and the porosity is 10 to 15%.

2. The fabrication process of the large-size graphitized furnace head conductive electrode according to claim 1, characterized in that, Graphitization was performed using a linear series-connected graphitization furnace. The power delivery curves for the first, second, third, and fourth stages were all linear; the power delivery curve for the fifth stage was as follows: Y=Z+154*X+511.75*X*X-32.72*X*X*X Y represents the power transmitted; X represents time; and Z represents the power transmitted at the end of the fourth stage.

3. The fabrication process of the large-size graphitized furnace head conductive electrode according to claim 2, characterized in that, The conductive electrode dimensions of the large-size graphitization furnace head are 3000-5000mm in length and 1400-2000mm in diameter.

4. The fabrication process of the large-size graphitized furnace head conductive electrode according to claim 3, characterized in that, The graphitization process is carried out using a linear series-connected graphitization furnace. The power supply curve during power supply is as follows: Initial power: 2415kW; In the first stage, the power was increased to 2920-2960kW, taking 6.3-6.5 hours; In the second stage, the power is reduced to 2430-2470kW, and the time taken is 3-3.2 hours; In the third stage, the power is increased to 5280-5330kW, and the time taken is 39.5-40.5 hours; In the fourth stage, the power increased to 6595kW, taking 6.3 to 6.5 hours; In the fifth stage, the power was increased to 12,000 kW, taking 3.5 hours; In the sixth stage, maintain a power of 12000kW for 2.4 to 2.5 hours; In the fifth stage, the power transmission curve is: Y = 6595 + 154 * X + 511.75 * X * X - 32.72 * X * X * X; Y represents the power transmitted; X represents the time.

5. The fabrication process of the large-size graphitized furnace head conductive electrode according to claim 1, characterized in that, The insulation material consists of 30%–40% graphitized metallurgical coke and 60%–70% metallurgical coke by volume.

6. The fabrication process of the large-size graphitized furnace head conductive electrode according to claim 1, characterized in that, The electrode blank is prepared from the following raw materials in parts by weight: 6-10 parts of sponge coke with a particle size of 6-9 mm; 42-49 parts of bullet coke with a particle size of 1-6 mm; 6-10 parts of bullet coke with a particle size of 0.5-1mm; 34-41 parts of petroleum coke with a particle size of less than 0.5 mm, consisting of 50% sponge coke and 50% pellet coke; 17-23 parts of coal tar pitch with a softening point of 105℃~115℃.

7. The fabrication process of the large-size graphitized furnace head conductive electrode according to claim 6, characterized in that, The electrode blank is prepared by the following steps: ingredient mixing, kneading, vibration molding, and baking in a baking furnace to obtain the electrode blank.

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