UHP phi 600 mm graphite male and female electrode for continuous graphitization furnace and preparation method thereof

Abstract

The application relates to a UHP Phi 600mm graphite male-female electrode for a continuous graphitization furnace and a preparation method thereof. The graphite male-female electrode is integrally formed, that is, a graphite male electrode and a graphite female electrode are integrally formed at two ends of the graphite male-female electrode in a concentric mode, the graphite male electrode and the graphite female electrode thereof can be connected through mutual thread cooperation, raw materials of the graphite male-female electrode include aggregates, iron powder and a plasticizer, raw materials of the aggregates include oil-based acicular coke, short carbon fibers, oil-based acicular coke powder and oil-based acicular coke superfine powder, the weight percentage of the iron powder is 0.5-1.0% of the aggregates, and the weight percentage of the plasticizer is 0.1-0.25% of the aggregates. The prepared graphite male-female electrode has the advantages of moderate bulk density, high bending strength, low elastic modulus, small thermal expansion coefficient and convenience in high-power current transmission.

Description

Technical Field

[0001] The present invention relates to the field of graphite electrodes, and in particular to a UHP Φ600mm graphite male and female electrode for a continuous graphitization furnace and a preparation method thereof. Background Art

[0002] Lithium battery anode materials have broad application prospects, with future growth primarily driven by power batteries and energy storage batteries. In the power battery market, demand for anode materials from new energy vehicles is expected to surge. In the energy storage market, numerous energy storage projects are entering the formal implementation phase, and the energy storage industry is entering a transition period from demonstration to commercialization. Based on the future application of lithium battery anode materials in power batteries, consumer batteries, and energy storage batteries, preliminary forecasts predict that demand for lithium battery anode materials will reach 1.27 million tons by 2026, with a compound annual growth rate of 25%.

[0003] The connection of the ultra-high power graphite electrode is connected through a double-cone threaded joint, and the raw materials, production process and technical conditions used for the graphite male electrode and the graphite electrode body are different, resulting in certain differences in the physical and chemical indicators and performance of the two. As a result, during use, the connection is prone to abnormal phenomena such as cracking and falling off, affecting the quality of the negative electrode material product. At the same time, the falling graphite electrode is easy to block the discharge port of the continuous graphitization furnace, resulting in discontinuous production. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies in the prior art and provide a UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace and a preparation method thereof. The prepared graphite male and female electrodes have moderate volume density, high flexural strength, low elastic modulus, and small thermal expansion coefficient; and can improve the safety and reliability of the connection between the graphite male and female electrodes and the graphite male electrode, reduce the contact resistance at the graphite male electrode, and facilitate the transmission of high-power current.

[0005] The present invention is achieved through the following technical solutions: on the one hand, a UHP Φ600mm graphite male and female electrode for a continuous graphitization furnace is provided, wherein the raw materials thereof include aggregate, iron powder and plasticizer; the raw materials of the aggregate are calculated by weight percentage and include 8% oil-based needle coke with a diameter of 11-22mm, 15% oil-based needle coke with a particle size of 6-11mm, 10% oil-based needle coke with a particle size of 4-6mm, 9% oil-based needle coke with a particle size of 2-4mm, 18% oil-based needle coke with a particle size of 0.5-2mm, 1% short carbon fiber, 35% oil-based needle coke powder, and 4% oil-based needle coke ultrafine powder; the weight percentage of the iron powder is 0.5-1.0% of the aggregate; the weight percentage of the plasticizer is 0.1-0.25% of the aggregate.

[0006] Through the above technical solution, the aggregate bulk density reaches 1.25g / cm3, and the graphite electrode prepared has a moderate volume density, high flexural strength, low elastic modulus, and small thermal expansion coefficient. In addition, adding a certain amount of iron powder to the total weight of the dry material can effectively prevent the product from expanding and cracking during graphitization. The weight of the iron powder is 0.5-1.0% of the aggregate, and the amount of iron powder is determined according to the sulfur content in the needle coke. The plasticizer can effectively improve the plasticity of the paste. The weight of the plasticizer is 0.1-0.25% of the aggregate. By adding the above-mentioned ultrafine powder and short fibers, the flexural strength of the product produced under the same process conditions is increased by about 15-20%, and the resistivity is reduced by 3-5%.

[0007] Furthermore, the needle coke particle size purity is ≥80%, the coke powder particle size is less than 0.074 mm, and the purity is 45±2%; the ultrafine coke powder particle size is less than 325 mesh, and the purity is 70±2%.

[0008] Through the above technical solution, the purity of needle coke particle size is limited. The particle size of coke powder is less than 0.074mm, and the purity is 45±2%; the particle size of ultrafine coke powder is less than 325 mesh, and the purity is 70±2%, which reflects the specific surface area of ​​coke powder, which can affect the amount of binder asphalt used, as well as the flexural strength of the product.

[0009] On the other hand, a method for preparing the above-mentioned UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace is provided, comprising the following specific steps:

[0010] (a) Batching: The raw materials of each size fraction in the above proportion are fed into an automatic batching system for batching to produce aggregate; (b) Kneading to produce a paste: The aggregate described in step (a) is added to a dry material heater and heated to approximately 140°C by power supply; the aggregates of each size fraction are then transferred to a kneading pot, 0.5% iron powder based on the total weight of the aggregate is added, mixed thoroughly, and then asphalt as a binder is added. The mixture is kneaded for 480 seconds and cooled by spraying water. When the temperature reaches 135°C, an appropriate amount of stearic acid is added and the cooling by spraying water is continued. When the paste temperature reaches 120°C, the paste is discharged; the discharged paste is allowed to rest in a pan for 30 minutes and then discharged into a press;

[0011] (c) Extrusion molding: The paste prepared in step (b) was fed to the feed chamber of a 30MN vertical ramming and horizontal extruder. After unloading, the feed chamber was evacuated to remove the smoke from the paste. When the vacuum reached 20 mmHg and was maintained for 180 seconds, a tamping operation was performed. The tamping pressure was 1350 tons and maintained for 120 seconds. After the tamping was completed, the tamping plunger was raised and the nozzle was rotated to the extrusion position to extrude the green body. The extrusion pressure was controlled at 600-1100 tons. After the extrusion was completed, the green body was turned over and placed in a 38°C cooling water tank for cooling. After being fished out, the surface temperature was controlled to be no more than 50°C, and the bulk density was measured;

[0012] (d) Primary calcination: The extruded product after extrusion molding in step (c) is allowed to stand for 48 hours, inspected and accepted according to the inspection specifications for extruded products, and after passing the inspection, is placed in a calcination pot and placed in a car bottom type calcination furnace for primary calcination. The temperature rise curve is controlled by using a 420 hour curve, with the temperature rising from 50°C to 170°C by increasing by 5°C per hour, which takes 24 hours; when the temperature is between 170°C and 440°C, the temperature is raised by 0.8-1.5°C per hour, which takes 225 hours. At 440-560℃, the temperature is increased by 2.5℃ per hour, which takes 48 hours; at 560-750℃, the temperature is increased by 4.5℃ per hour, which takes 47.5 hours; at 750-850℃, the temperature is increased by 8℃ per hour, which takes 12.5 hours; at 850℃, the temperature is kept constant for 24 hours; at 850-300℃, the temperature is lowered by 14℃, which takes 39.3 hours; the product is taken out of the furnace and naturally cooled to room temperature before being taken out of the can, and the product is inspected.

[0013] (e) Impregnation: The qualified primary calcined parts are placed in a preheating tank and preheated to a temperature greater than 360°C and maintained at this temperature for 10 hours. They are then transferred to an impregnation tank and evacuated to -85 kPa and maintained at this temperature for 60 minutes. Impregnation pitch is then injected and pressurized to 13-15 bar and maintained for 1.5 hours. After the impregnation is completed, the pitch is extracted, cooled with cooling water, and then removed from the tank to obtain the impregnated product.

[0014] (f) Secondary calcination: The impregnated product is placed in an open firing frame and subjected to secondary calcination in a cart-type calciner. The temperature rise curve is controlled by the 96.7-hour curve; the temperature is raised by 20°C per hour at 65-325°C, taking 13 hours; the temperature is raised by 9°C per hour at 325-493°C, taking 18.6 hours; the temperature is raised by 24°C per hour at 493-800°C, taking 12.3 hours; the temperature is maintained at 800°C for 10 hours; and the temperature is lowered by 14°C at 850-200°C, taking 42.8 hours. The product is then removed from the furnace and allowed to cool naturally to room temperature before being removed from the can. The secondary calcined product is then inspected.

[0015] (g) Graphitization treatment: The qualified secondary calcined products are placed in an internal string graphitization furnace for graphitization treatment, and the graphitization curve uses a 17-hour curve; in the room temperature-800°C stage, the heating rate is controlled at 200-220°C / h, and the graphitization treatment is carried out for 3.5 hours; then, in the 800-1800°C stage, the heating rate is controlled at 150-200°C / h, and the graphitization treatment is carried out for 6.5 hours; in the 1800-2200°C stage, the heating rate is controlled at 90-100°C / h, and the graphitization treatment is carried out for 4 hours; in the 2200-3000°C stage, the heating rate is controlled at 180-310°C / h, and the graphitization treatment is carried out for 3.5 hours; after the power supply is completed and 48 hours later, the products are cooled by spraying water (8 hours), and naturally cooled for one week before being removed from the furnace. After being removed from the furnace, the graphite electrode products are sampled and inspected;

[0016] (h) The graphite electrode product obtained in step (g) is tested according to the specified technical requirements, processed into a finished product of specified specifications, subjected to strict index and dimensional inspection, and then pre-assembled, packaged, and stored according to the specified matching requirements.

[0017] By the above technical solution, in step (c), the bulk density is measured, and the bulk density is uniformly 1.75 g / cm 3 and pass the appearance and sound inspection;

[0018] In step (d), the test results are as follows: Bulk density: 1.67-1.68 g / cm 3 , resistivity: 40-45μΩ·m, actual recovery rate 92.90%, length shrinkage 1.85%, outer diameter shrinkage 0.8%, and passed the appearance and sound inspection;

[0019] In step (e), the weight gain rate of the obtained impregnated product is above 11.5%;

[0020] In step (f), the test results are as follows: Bulk density: 1.77-1.78 g / cm 3 , resistivity: 35-40μΩ·m, recovery rate 95.17%;

[0021] In step (g), the sampling test results are as follows: Bulk density: 1.73-1.75g / cm 3 , resistivity: 4.6-4.8μΩ·m, thermal expansion coefficient: 1.28×10 6 / ℃, flexural strength: 11.02-12.86Mpa, elastic modulus: 8.1-9.6Gpa, ash content: 0.03%.

[0022] Through the above technical solution, the graphite male electrode and the graphite female electrode have the same raw materials, the same preparation process, the same physical and chemical properties, and the threaded connection is more perfect.

[0023] Furthermore, the graphite male electrode protrudes from one end of the graphite electrode product, and the graphite male electrode is not threaded at a distance of 4.5 mm to 5 mm from the graphite electrode product.

[0024] Furthermore, the graphite male electrode is processed into an arc with a radius of 6.30 mm from the thread crest at the maximum diameter of the thread to the expanded diameter, and the arc is tangent to the straight line connecting the thread crest.

[0025] Through the above technical solution, the graphite male electrode is not threaded at a distance of 4.5mm-5mm from the graphite electrode product in order to process an arc with a radius of 6.30mm. According to the principles of mechanics, the arc is convenient for force dispersion and prevents stress concentration from causing product breakage.

[0026] Furthermore, the graphite mother electrode is recessed at one end of the graphite electrode product, and the graphite mother electrode is not threaded at a position 5.50-6.00 mm away from the end face of the graphite electrode product.

[0027] Furthermore, the graphite mother electrode is processed into an oblique straight line from the bottom of the thread at the maximum diameter of the thread to the expanded diameter.

[0028] Through the above technical solution, the graphite mother electrode is not threaded at a position 5.50-6.00 mm away from the end face of the graphite electrode product in order to match the connection of the arc at the joint end.

[0029] The beneficial effect of the present invention is that the volume density of the prepared graphite electrode is moderate, 1.73-1.75 g / cm 3 , the flexural strength is increased by 10-15%, the resistivity is reduced by 5-8%, and the thermal expansion coefficient is reduced by 5-10%; and it can improve the safety and reliability of the connection between the graphite electrode and the graphite male electrode, reduce the contact resistance at the graphite male electrode, and facilitate the transmission of high-power current. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of the graphite electrode and the graphite male electrode embodied in the present invention.

[0031] Among them, 1-graphite electrode products; 2-graphite male electrode; 3-graphite female electrode. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] Example 1

[0034] A UHP Φ600mm graphite male and female electrode for a continuous graphitization furnace, the raw materials of which include aggregate, iron powder and plasticizer; the raw materials of the aggregate include, by weight percentage, 8% oil-based needle coke with a particle size of 11-22mm, 15% oil-based needle coke with a particle size of 6-11mm, 10% oil-based needle coke with a particle size of 4-6mm, 9% oil-based needle coke with a particle size of 2-4mm, 18% oil-based needle coke with a particle size of 0.5-2mm, 1% short carbon fiber, 35% oil-based needle coke powder, and 4% oil-based needle coke ultrafine powder; the weight percentage of the iron powder is 0.5-1.0% of the aggregate; the weight percentage of the plasticizer is 0.1-0.25% of the aggregate.

[0035] Based on the above technical solution, the aggregate bulk density reaches 1.25g / cm3, and the graphite electrode prepared has moderate volume density, high flexural strength, low elastic modulus, and small thermal expansion coefficient. In addition, adding a certain amount of iron powder to the total weight of the dry material can effectively prevent the product from expanding and cracking in the graphitized electrode. The weight of the iron powder is 0.5-1.0% of the aggregate, and the amount of iron powder is determined according to the sulfur content in the needle coke. The plasticizer can effectively improve the plasticity of the paste. The weight of the plasticizer is 0.1-0.25% of the aggregate. By adding the above-mentioned ultrafine powder and short fibers, the flexural strength of the product produced under the same process conditions is increased by about 15-20%, and the resistivity is reduced by 3-5%.

[0036] Furthermore, the needle coke particle size purity is ≥80%, the coke powder particle size is less than 0.074 mm, and the purity is 45±2%; the ultrafine coke powder particle size is less than 325 mesh, and the purity is 70±2%.

[0037] Through the above technical solution, the purity of needle coke particle size is limited. The particle size of coke powder is less than 0.074mm, and the purity is 45±2%; the particle size of ultrafine coke powder is less than 325 mesh, and the purity is 70±2%. These characteristics reflect the specific surface area of ​​coke powder, which can affect the amount of binder asphalt used and the flexural strength of the product.

[0038] On the other hand, a method for preparing the above-mentioned UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace is provided, comprising the following specific steps:

[0039] (a) Batching: The raw materials of each particle size in the above proportion are fed into an automatic batching system for batching to obtain aggregate;

[0040] (b) kneading to prepare a paste: The aggregate described in step (a) is added to a dry material heater and heated to approximately 140°C by power. The aggregates of each size fraction are then transferred to a kneading pot, and 0.5% iron powder based on the total weight of the aggregates is added and mixed thoroughly. After that, a binder, asphalt, is added and kneaded for 480 seconds. The mixture is then cooled by spraying water. When the temperature reaches 135°C, an appropriate amount of stearic acid is added and the cooling by spraying water is continued. When the temperature of the paste reaches 120°C, the paste is discharged. The discharged paste is allowed to rest in a pan for 30 minutes and then discharged into a press.

[0041] (c) Extrusion molding: The paste prepared in step (b) was fed to the material chamber of a 30MN vertical ramming and horizontal extruder. After unloading, the material chamber was evacuated to remove the smoke of the paste. When the vacuum reached 20 mmHg and was maintained for 180 seconds, a tamping operation was performed. The tamping pressure was 1350 tons and maintained for 120 seconds. After the tamping was completed, the tamping plunger was lifted and the nozzle was rotated to the extrusion position to extrude the green body. The extrusion pressure was controlled at 600-1100 tons. After the extrusion was completed, the green body was turned over and cooled in a 38°C cooling water tank. The surface temperature was controlled to be no more than 50°C after being fished out. The bulk density was measured and the uniform bulk density was 1.75 g / cm 3 and pass the appearance and sound inspection;

[0042] (d) Primary calcination: The extruded product after extrusion molding in step (c) is allowed to stand for 48 hours, inspected and accepted according to the inspection specifications for extruded products, and after passing the inspection, is placed in a calcination pot and placed in a car bottom type calcination furnace for primary calcination. The temperature rise curve is controlled by using a 420 hour curve, with the temperature rising from 50°C to 170°C increasing by 5°C per hour for 24 hours; at 170-440°C, the temperature is raised by 0.8-1.5°C per hour for 225 hours, and at 440-5 At 60℃, the temperature is increased by 2.5℃ per hour, which takes 48 hours; at 560-750℃, the temperature is increased by 4.5℃ per hour, which takes 47.5 hours; at 750-850℃, the temperature is increased by 8℃ per hour, which takes 12.5 hours; at 850℃, the temperature is kept constant for 24 hours; at 850-300℃, the temperature is lowered by 14℃, which takes 39.3 hours; the product is taken out of the furnace and naturally cooled to room temperature before being taken out of the can. The product is then inspected; the inspection results are as follows: Bulk density: 1.67-1.68g / cm 3 , resistivity: 40-45μΩ·m, actual recovery rate 92.90%, length shrinkage 1.85%, outer diameter shrinkage 0.8%, and passed the appearance and sound inspection;

[0043] (e) Impregnation: The qualified primary calcined parts are placed in a preheating tank and preheated to a temperature greater than 360°C for 10 hours. The parts are then transferred to an impregnation tank and vacuumed to -85kPa and maintained for 60 minutes. The impregnation pitch is then injected and pressurized to 13-15bar and maintained for 1.5 hours. After the impregnation is completed, the pitch is extracted, cooled with cooling water, and then removed from the tank to obtain the impregnated product. The weight gain of the obtained impregnated product is greater than 11.5%.

[0044] (f) Secondary calcination: The impregnated product is placed in an open firing frame and subjected to secondary calcination in a car bottom calcination furnace. The temperature rise curve is controlled by the 96.7 hour curve; the temperature is raised by 20°C per hour at 65-325°C, which takes 13 hours; the temperature is raised by 9°C per hour at 325-493°C, which takes 18.6 hours; the temperature is raised by 24°C per hour at 493-800°C, which takes 12.3 hours; the temperature is kept constant at 800°C for 10 hours; the temperature is lowered by 14°C at 850-200°C, which takes 42.8 hours; the product is taken out of the furnace and naturally cooled to room temperature before being taken out of the can. The secondary calcined product is inspected; the inspection results are as follows: Bulk density: 1.77-1.78 g / cm 3 , resistivity: 35-40μΩ·m, recovery rate 95.17%;

[0045] (g) Graphitization treatment: The qualified secondary calcined products are placed in an internal graphitization furnace for graphitization treatment, and the graphitization curve uses a 17-hour curve; in the room temperature-800℃ stage, the heating rate is controlled at 200-220℃ / h, and the graphitization treatment is 3.5 hours; then in the 800-1800℃ stage, the heating rate is controlled at 150-200℃ / h, and the graphitization treatment is 6.5 hours; in the 1800-2200℃ stage, the heating rate is controlled at 90-100℃ / h, and the graphitization treatment is 4 hours; in the 2200-3000℃ stage, the heating rate is controlled at 180-310℃ / h, and the graphitization treatment is 3.5 hours; after the power supply is completed, water is sprayed (8 hours) for cooling (8 hours), and the products are naturally cooled for one week before being taken out of the furnace. After being taken out of the furnace, the graphite electrode products (1) are sampled and inspected; the sampling inspection results are as follows: Bulk density: 1.73-1.74g / cm 3 , resistivity: 4.6-4.8μΩ·m, thermal expansion coefficient: 1.28×10 6 / ℃, flexural strength: 11.02-12.86Mpa, elastic modulus: 8.1-9.6Gpa, ash content: 0.03%.

[0046] (h) The graphite electrode product (1) obtained in step (g) is tested according to the specified technical requirements, processed into a finished product of specified specifications, subjected to strict index and dimensional inspection, and then pre-assembled, packaged, and stored according to the specified matching requirements.

[0047] In order to solve the problem that the existing graphite electrode connection is connected through the graphite electrode body and the graphite electrode joint, the graphite electrode body and the graphite electrode joint use different raw materials and production processes, resulting in relatively large differences in the physical and chemical indicators of the products, resulting in large differences in antioxidant performance. During use, it was found that the joint fell off due to the complete oxidation of the body, blocking the discharge port and affecting the production rhythm. Technical problem.

[0048] On the basis of the above scheme, the graphite male and female electrodes of the present invention are connected by processing themselves into threads; specifically, in step (h), as Figure 1 As shown, a graphite electrode product (1) is integrally formed with a concentrically arranged graphite male electrode (2) and a graphite female electrode (3) at both ends, and the graphite male electrode (2) and the graphite female electrode (3) are threadedly connected to each other; the prepared graphite male and female electrodes have a moderate volume density, a 10-15% increase in flexural strength, a 5-8% decrease in resistivity, and a 5-10% decrease in thermal expansion coefficient; and can improve the safety and reliability of the connection between the graphite female electrode and the graphite male electrode, reduce the contact resistance at the graphite male electrode, and facilitate the transmission of high-power current.

[0049] On the basis of the above scheme, when the volume density of the existing graphite electrode is low, the porosity is high and the oxidation resistance is poor, and at the same time, the product flexural strength is low and is prone to breakage and other abnormal conditions; when the volume density of the graphite electrode is high, although the flexural strength of the product increases, the elastic modulus is also significantly increased, the brittleness of the product increases, and it is also prone to breakage and other abnormal conditions; it is well known to those skilled in the art that flexural strength is an important indicator of product strength performance, the flexural strength of the existing graphite electrode is 10-11 MPa, and the flexural strength of the graphite electrode product (1) prepared by the present invention is 11.02-12.86 MPa; the resistivity of the existing graphite electrode is about 5.0 μΩ·m, while the formula resistance of the graphite electrode product (1) prepared by the present invention is 4.6-4.8 μΩ·m;

[0050] Furthermore, if Figure 1 As shown, the graphite male electrode (2) protrudes from one end of the graphite electrode product (1), and the graphite male electrode (2) is not threaded at a distance of 4.5mm-5mm from the graphite electrode product (1); the graphite male electrode (2) is processed from the thread crest at the maximum diameter of the thread to the expanded diameter to form an arc with a radius of 6.30mm, and the arc is tangent to the straight line connected to the thread crest (the specific processing method is that the graphite male electrode (2) and the thread crest at the maximum diameter to the expanded diameter are processed to form an arc with a radius of 6.30mm respectively, and the graphite male electrode (2) is processed into a single-taper thread by a single cutter. In order to increase the strength of the graphite male electrode (2) and disperse the force points, an arc is added). The specific graphite male electrode processing process parameters are shown in Table 1 below:

[0051] Table 1 Graphite male electrode (electrode protruding part) thread processing parameters

[0052] Length (mm) 228.60-228.55 Median diameter (mm) 313.89-314.19 Large diameter(mm) 317.05-317.35 Empty tool value (mm) 0～10 Single thread pitch (mm) 6.30-6.35 tooth shape half angle 30°±15′ Accuracy range 18°53′29″-18°55′29″ Roundness error (mm) ≤0.1 Outer diameter (mm) 323.00-323.50

[0053] Furthermore, the graphite mother electrode (3) is recessed at one end of the graphite electrode product (1), and the graphite mother electrode (3) is not threaded at a distance of 5.50-6.00 mm from the end face of the graphite electrode product (1); the graphite mother electrode (3) is processed into an oblique straight line from the bottom of the thread at the maximum diameter of the thread to the outer diameter (the specific processing method is that the graphite male electrode (2) and the bottom of the thread at the maximum diameter of the thread to the outer diameter are processed into an oblique straight line separately, and the graphite mother electrode (3) is also processed into a single-taper thread by a combing knife; in order to facilitate the connection with the arc of the graphite male electrode (2), the bottom of the thread at the maximum diameter of the thread of the graphite mother electrode (3) to the outer diameter is processed into an oblique straight line, so that the graphite male electrode (2) and the graphite mother electrode (3) are connected). Specific processing parameters of the graphite mother electrode are shown in Table 2 below:

[0054] Table 2 Processing parameters of graphite mother electrode (electrode concave part)

[0055] Hole depth (mm) 234.50-235.00 Thread length (mm) 225.00-235.00 Outer diameter (mm) 323.50-323.60 Minor diameter (mm) 311.18-311.48 Median diameter (mm) 314.34-314.64 Single thread pitch (mm) 6.30-6.35 tooth shape half angle 30°±15′ Accuracy range 18°55′29″-18°57′29″ Roundness error (mm) ≤0.1 Flatness (mm) ≤0.05 Verticality (mm) ≤0.1 Coaxiality (mm) ≤0.3

[0056] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A UHP Φ600mm graphite male and female electrode for a continuous graphitization furnace, characterized in that: It comprises integrally formed graphite male and female electrodes, i.e., a concentrically arranged graphite male electrode (2) and a graphite female electrode (3) are integrally formed at both ends of the graphite male and female electrodes, and the graphite male electrode (2) and its graphite female electrode (3) can be threadedly connected to each other; The graphite male electrode (2) protrudes from one end of the graphite electrode product (1), and the graphite male electrode (2) is not threaded at a distance of 4.5 mm to 5 mm from the graphite electrode product (1); the graphite male electrode (2) is processed into an arc with a radius of 6.30 mm from the thread crest at the maximum diameter of the thread to the expanded diameter, and the arc is tangent to the straight line connecting the thread crest; The graphite mother electrode (3) is recessed at one end of the graphite electrode product (1), and the graphite mother electrode (3) is not threaded at a distance of 5.50-6.00 mm from the end face of the graphite electrode product (1); the graphite mother electrode (3) is processed into an oblique straight line from the bottom of the thread at the maximum diameter of the thread to the expanded diameter; the graphite mother electrode (3) is processed into a single-taper thread by a combing knife; the graphite mother electrode (3) is processed into an oblique straight line from the bottom of the thread at the maximum diameter of the thread to the expanded diameter.

2. The UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to claim 1, characterized in that: The raw materials of the graphite male and female electrodes include aggregate, iron powder and plasticizer; the raw materials of the aggregate include, by weight percentage, 8% oil-based needle coke with a particle size of 11-22 mm, 15% oil-based needle coke with a particle size of 6-11 mm, 10% oil-based needle coke with a particle size of 4-6 mm, 9% oil-based needle coke with a particle size of 2-4 mm, 18% oil-based needle coke with a particle size of 0.5-2 mm, 1% short carbon fiber, 35% oil-based needle coke powder, and 4% oil-based needle coke ultrafine powder; the weight percentage of the iron powder is 0.5-1.0% of the aggregate; the weight percentage of the plasticizer is 0.1-0.25% of the aggregate.

3. The UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to claim 2, characterized in that: The needle coke particle size purity is ≥80%, the coke powder particle size is less than 0.074 mm, and the purity is 45±2%; the ultrafine coke powder particle size is less than 325 mesh, and the purity is 70±2%.

4. A method for preparing the UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to any one of claims 1 to 3, characterized in that: The specific steps include: (a) Batching: The raw materials of different particle sizes in the proportion are fed into the automatic batching system for batching to obtain aggregate; (b) kneading to prepare a paste: The aggregate described in step (a) is added to a dry material heater and heated to approximately 140°C by power. The aggregates of each size fraction are then transferred to a kneading pot, and 0.5% iron powder based on the total weight of the aggregates is added and mixed thoroughly. After that, a binder, asphalt, is added and kneaded for 480 seconds. The mixture is then cooled by spraying water. When the temperature reaches 135°C, an appropriate amount of stearic acid is added and the cooling by spraying water is continued. When the temperature of the paste reaches 120°C, the paste is discharged. The discharged paste is allowed to rest in a pan for 30 minutes and then discharged into a press. (c) Extrusion molding: The paste prepared in step (b) was fed to the feed chamber of a 30MN vertical ramming and horizontal extruder. After unloading, the feed chamber was evacuated to remove the smoke from the paste. When the vacuum reached 20 mmHg and was maintained for 180 seconds, a tamping operation was performed. The tamping pressure was 1350 tons and maintained for 120 seconds. After the tamping was completed, the tamping plunger was lifted and the nozzle was rotated to the extrusion position to extrude the green body. The extrusion pressure was controlled at 600-1100 tons. After the extrusion was completed, the green body was turned over and placed in a 38°C cooling water tank for cooling. After being fished out, the surface temperature was controlled to be no more than 50°C, and the bulk density was measured; (d) Primary calcination: The extruded product after extrusion molding in step (c) is allowed to stand for 48 hours, inspected and accepted according to the inspection specifications for extruded products, and after passing the inspection, is placed in a calcination pot and placed in a car bottom type calcination furnace for primary calcination. The temperature rise curve is controlled by using a 420 hour curve, with the temperature rising from 50°C to 170°C by increasing by 5°C per hour, which takes 24 hours; when the temperature is between 170°C and 440°C, the temperature is raised by 0.8-1.5°C per hour, which takes 225 hours. At 440-560℃, the temperature is increased by 2.5℃ per hour, which takes 48 hours; at 560-750℃, the temperature is increased by 4.5℃ per hour, which takes 47.5 hours; at 750-850℃, the temperature is increased by 8℃ per hour, which takes 12.5 hours; at 850℃, the temperature is kept constant for 24 hours; at 850-300℃, the temperature is lowered by 14℃, which takes 39.3 hours; the product is taken out of the furnace and naturally cooled to room temperature before being taken out of the can, and the product is inspected. (e) Impregnation: The qualified primary calcined parts are placed in a preheating tank and preheated to a temperature greater than 360°C and maintained at this temperature for 10 hours. They are then transferred to an impregnation tank and evacuated to -85 kPa and maintained at this temperature for 60 minutes. Impregnation pitch is then injected and pressurized to 13-15 bar and maintained for 1.5 hours. After the impregnation is completed, the pitch is extracted, cooled with cooling water, and then removed from the tank to obtain the impregnated product. (f) Secondary calcination: The impregnated product is placed in an open firing frame and subjected to secondary calcination in a cart-type calciner. The temperature rise curve is controlled by the 96.7-hour curve; the temperature is increased by 20°C per hour at 65-325°C, taking 13 hours; the temperature is increased by 9°C per hour at 325-493°C, taking 18.6 hours; the temperature is increased by 24°C per hour at 493-800°C, taking 12.3 hours; at 800°C, the temperature is maintained constant for 10 hours; and the temperature is reduced by 14°C at 850-200°C, taking 42.8 hours. The product is then removed from the furnace and naturally cooled to room temperature before being canned. The secondary calcined product is then inspected. (g) Graphitization treatment: The qualified secondary calcined product is placed in an internal string graphitization furnace for graphitization treatment, and the graphitization curve uses a 17-hour curve; in the room temperature-800°C stage, the heating rate is controlled at 200-220°C / h, and the graphitization treatment is 3.5 hours; then in the 800-1800°C stage, the heating rate is controlled at 150-200°C / h, and the graphitization treatment is 6.5 hours; in the 1800-2200°C stage, the heating rate is controlled at 90-100°C / h, and the graphitization treatment is 4 hours; in the 2200-3000°C stage, the heating rate is controlled at 180-310°C / h, and the graphitization treatment is 3.5 hours; after the power supply is completed and 48 hours later, water is sprayed for cooling for 8 hours, and the product is naturally cooled for one week before being taken out of the furnace. After being taken out of the furnace, the graphite electrode product (1) is sampled and inspected; (h) The graphite electrode product (1) obtained in step (g) is tested according to the specified technical requirements, processed into a finished product of specified specifications, subjected to strict index and dimensional inspection, and then pre-assembled, packaged, and stored according to the specified matching requirements.

5. The method for preparing UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to claim 4, characterized in that: The graphite male electrode (2) protrudes from one end of the graphite electrode product (1), and the graphite male electrode (2) is not threaded at a distance of 4.5 mm to 5 mm from the graphite electrode product (1).

6. The method for preparing UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to claim 5, characterized in that: The graphite male electrode (2) is processed into an arc with a radius of 6.30 mm from the thread crest at the maximum diameter of the thread to the expanded diameter, and the arc is tangent to the straight line connecting the thread crest.

7. The method for preparing UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to claim 4, characterized in that: The graphite mother electrode (3) is recessed at one end of the graphite electrode product (1), and the graphite mother electrode (3) is not threaded at a distance of 5.50-6.00 mm from the end face of the graphite electrode product (1).

8. The method for preparing UHP Φ600mm graphite male and female electrodes for a continuous graphitization furnace according to claim 7, characterized in that: The graphite mother electrode (3) is machined into an oblique straight line from the bottom of the thread where the thread has the maximum diameter to the expanded diameter.

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