An antioxidant and corrosion-resistant prebaked anode and its preparation method

Abstract

This invention relates to the field of prebaked anode technology, and more particularly to an antioxidant and corrosion-resistant prebaked anode and its preparation method. The raw materials for the aforementioned antioxidant and corrosion-resistant prebaked anode include: calcined petroleum coke, coal tar pitch, calcined coke, and additives, with a mass ratio of 100:14.2-15.2:5-15:1-5. The calcined petroleum coke comprises: coarse coke with a particle size of 5-10 mm, medium coke with a particle size of 1-5 mm, and fine coke with a particle size of 0.1-1 mm. The coarse coke accounts for 30-40% of the mass percentage of the calcined petroleum coke, the medium coke accounts for 30-40% of the mass percentage of the calcined petroleum coke, and the remainder is fine coke. This invention effectively improves the density and antioxidant capacity of the prebaked anode, reduces air permeability, and achieves a synergistic optimization and improvement of conductivity and density properties.

Description

Technical Field

[0001] This invention relates to the field of prebaked anode technology, and in particular to an antioxidant and corrosion-resistant prebaked anode and its preparation method. Background Technology

[0002] Prebaked anodes, also known as prebaked anode blocks or carbon anodes for aluminum electrolysis, are manufactured using petroleum coke and pitch coke as aggregates and coal tar pitch as a binder. They are used as the anode material in prebaked aluminum electrolytic cells, serving the dual purpose of conducting electricity and participating in chemical reactions. Aluminum electrolytic cells using prebaked anodes are called prebaked anode electrolytic cells, or simply prebaked cells, and are a type of large-scale aluminum electrolytic cell.

[0003] Currently, the production of anode carbon blocks generally uses petroleum coke as raw material and coal tar pitch as a binder. The process involves petroleum coke calcination, medium crushing, screening, fine crushing, asphalt melting, batching, mixing, molding, and roasting. Prebaked anodes, having undergone roasting treatment, possess excellent electrical conductivity and high-temperature corrosion resistance, making them an important component of the aluminum industry's supporting industries. Their main functions include: acting as an anode conductor to conduct current, participating in electrochemical reactions, and providing some energy for the thermal balance during electrolysis.

[0004] The quality of prebaked anodes has a significant impact on the current efficiency, power consumption, product grade, and economic and technical indicators of electrolytic aluminum production. Meanwhile, prebaked anodes are also widely used in chemical, power, and metallurgical industries, where corrosion protection is required. As an additional protective layer, they cover the metal surface to resist environmental corrosive factors, extend service life, and improve safety performance.

[0005] In the aluminum electrolysis industry, prebaked anodes are a key material. However, the simple composite of petroleum coke and coal tar pitch makes it difficult to construct an efficient conductive network, resulting in a tortuous electron transport path. On the one hand, this makes the anode susceptible to oxidation and corrosion in the high-temperature electrolysis environment, and uneven current distribution causes localized overheating, accelerating the consumption of anode material. On the other hand, it results in insufficient structural density, leading to electrolyte penetration and shortening service life. More seriously, the current process excessively pursues conductivity at the expense of structural strength, while simply increasing density may increase cost. This technological shortcoming is becoming increasingly prominent in the process of large-scale aluminum electrolysis cells. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing an antioxidant and corrosion-resistant prebaked anode and its preparation method.

[0007] An antioxidant and corrosion-resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined coke, and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined coke, and additives is 100:14.2-15.2:5-15:1-5; the calcined petroleum coke includes: coarse coke with a particle size of 5-10 mm, medium coke with a particle size of 1-5 mm, and fine coke with a particle size of 0.1-1 mm; the coarse coke accounts for 30-40% of the mass percentage of the calcined petroleum coke, the medium coke accounts for 30-40% of the mass percentage of the calcined petroleum coke, and the remainder is fine coke.

[0008] Among them, calcined petroleum coke is obtained by calcining petroleum coke at high temperature and then crushing, screening and grading it in sequence; calcined coke is obtained by crushing unqualified prebaked anode products.

[0009] Preferably, the room temperature resistivity of the antioxidant and corrosion resistant prebaked anode is ≤56μΩ·m, and the withstand voltage is ≥42.7MPa.

[0010] Preferably, the softening point of the coal tar pitch is 105-115℃, and the coking value is 54-58%.

[0011] Preferably, the raw materials of the additive include, by mass, 60-80 parts graphite powder, 10-20 parts vapor-grown carbon fiber, 1-3 parts activated nano-silica, and 1-10 parts hexagonal boron nitride nanosheets.

[0012] More preferably, the activated nano-silica is nano-silica activated by silane coupling agent KH550.

[0013] More preferably, the graphite powder has a particle size D50 of 5 μm.

[0014] More preferably, the activated nano-silica particles have a particle size of 20-50 nm.

[0015] More preferably, the vapor-grown carbon fiber has a diameter of 50-150 nm and an aspect ratio of 25-35.

[0016] Preferably, the additive is prepared by the following specific operation: adding vapor-grown carbon fibers and activated nano-silica to graphite powder, mixing and grinding evenly, and then adding hexagonal boron nitride nanosheets and grinding evenly.

[0017] Preferably, the raw materials also include: silica sol, wherein the mass ratio of silica sol to calcined silica sol is 0.05-0.2:1.

[0018] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0019] S1. After crushing the calcined coal tar pitch, sieve it and mix it with calcined petroleum coke. Knead it at 140-150℃ for 10-20 minutes. Add the molten coal tar pitch and additives and knead it at 190-200℃ for 10-20 minutes. Vibrate it for 1-3 minutes at a vibration frequency of 20-30Hz. Keep the temperature at 140-150℃ during the vibration process to obtain the green body.

[0020] S2. Cool the embryo to room temperature, raise the temperature to 400-500℃ at 15-30℃ / h, hold for 1-2 hours, continue to raise the temperature to 600-800℃, hold for 2-6 hours; seal, then raise the temperature to 1000-1100℃ at 10-20℃ / h, hold for 20-40 hours, and cool to below 250℃.

[0021] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0022] S1. After crushing the calcined coal, sieve it and spray an ethanol-water solution containing silica sol onto its surface. Heat treat it at 300-400℃ for 10-30 minutes. Then mix it with calcined petroleum coke and knead it at 140-150℃ for 10-20 minutes. Add molten coal tar pitch and additives and knead it at 190-200℃ for 10-20 minutes. Vibrate it for 1-3 minutes at a vibration frequency of 20-30Hz. Maintain the temperature at 140-150℃ during the vibration process to obtain a green body.

[0023] S2. Cool the embryo to room temperature, raise the temperature to 400-500℃ at 15-30℃ / h, hold for 1-2 hours, continue to raise the temperature to 600-800℃, hold for 2-6 hours; seal, then raise the temperature to 1000-1100℃ at 10-20℃ / h, hold for 20-40 hours, and cool to below 250℃.

[0024] Beneficial effects:

[0025] This invention employs a three-dimensional conductive framework formed by vapor-grown carbon fibers with a high aspect ratio and layered graphite powder to create a continuous conductive pathway in the matrix. This framework not only exhibits excellent stability but also significantly reduces the electron transport barrier due to the multi-scale conductive network. Simultaneously, nano-silica fills the pores, reducing electron scattering and greatly lowering the resistivity.

[0026] This invention utilizes the synergistic effect of a silica sol coating layer and hexagonal boron nitride nanosheets to achieve a dual improvement in density and oxidation resistance. After heat treatment, the silica sol forms an amorphous SiO2 protective layer, effectively sealing the surface pores of the carbon matrix and blocking oxygen diffusion paths. Meanwhile, the layered structure of the hexagonal boron nitride nanosheets, interspersed between graphite layers, effectively reduces microcrack formation by inhibiting interlayer slippage. Simultaneously, its chemical inertness delays the carbon-oxygen reaction. The combined effect of these two technologies improves density while effectively shortening the oxygen ion diffusion path.

[0027] This invention achieves synergy between adjusting the amount of asphalt and the vibration time, thereby regulating the distribution of the binder phase. Excessive asphalt hinders particle contact, while insufficient vibration leads to increased porosity. By optimizing process parameters, this invention enables the green body to form a uniform composite structure. After calcination, the interfacial bonding strength between the carbon matrix and the aggregate is significantly enhanced, thus improving thermal shock resistance.

[0028] This invention effectively improves the density and oxidation resistance of prebaked anodes while reducing air permeability. The prebaked anode exhibits excellent performance, with a room temperature resistivity of 56 μΩ•m and an apparent density of 1.57 g / cm³. 3 The true density is 2.072 g / cm³. 3 This technology achieves a synergistic optimization and improvement of conductivity and density, significantly enhances the stability of prebaked anodes, has low consumption, long service life, and is suitable for large-scale application. Attached Figure Description

[0029] Figure 1 This is a photograph of the prebaked anode obtained in Example 5.

[0030] Figure 2 The above diagram shows a comparison of the apparent density and true density of the prebaked anodes obtained in Examples 5, 6, 1, and 2.

[0031] Figure 3 The chart shows a comparison of the room temperature resistivity and withstand voltage of the prebaked anodes obtained in Examples 5, 6, 1, and 2.

[0032] Figure 4 The chart shows a comparison of the air reaction residue rate and air permeability of the prebaked anodes obtained in Examples 5, 6, 1, and 2. Detailed Implementation

[0033] The present invention will be further explained below with reference to specific embodiments.

[0034] The coal tar pitch used below has a softening point of 108.2℃ and a coking value of 56.3%. The activated nano-silica used below was obtained by activating nano-silica with a particle size of 20-50 nm using the silane coupling agent KH550. The graphite powder used below has a particle size D50 of 5 μm. The vapor-grown carbon fiber used below (VGCF, grade PR-24, Applied Science) has a diameter of 100±40 nm and an aspect ratio of approximately 30.

[0035] Example 1

[0036] An antioxidant and corrosion-resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives is 100:14.2:15:1.

[0037] Calcined petroleum coke comprises, by mass percentage: 40% coarse coke with a particle size of 5-10 mm, 30% medium coke with a particle size of 1-5 mm, and the remainder fine coke with a particle size of 0.1-1 mm.

[0038] The additive is prepared by the following specific operation: 10g of vapor-grown carbon fiber and 3g of activated nano-silica are added to 80g of graphite powder and mixed and ground evenly. Then, 1g of hexagonal boron nitride nanosheets are added and ground evenly.

[0039] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0040] S1. After crushing and screening, the calcined petroleum coke is mixed with calcined petroleum coke and kneaded at 150°C for 10 minutes. Molten coal tar pitch and additives are added and kneaded at 200°C for 10 minutes. The mixture is then vibrated and molded for 3 minutes at a vibration frequency of 20 Hz. The temperature is maintained at 150°C during the vibration process to obtain the green body.

[0041] S2. Cool the embryo to room temperature, raise the temperature to 500℃ at 15℃ / h, hold for 1h, continue to raise the temperature to 800℃, hold for 2h; seal, then raise the temperature to 1000℃ at 10℃ / h, hold for 40h, and cool to below 250℃.

[0042] Example 2

[0043] An antioxidant and corrosion-resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives is 100:15.2:5:5.

[0044] Calcined petroleum coke comprises, by mass percentage: 30% coarse coke with a particle size of 5-10 mm, 40% medium coke with a particle size of 1-5 mm, and the remainder fine coke with a particle size of 0.1-1 mm.

[0045] The additive is prepared by the following specific operation: 20g of vapor-grown carbon fiber and 1g of activated nano-silica are added to 60g of graphite powder and mixed and ground evenly. Then, 10g of hexagonal boron nitride nanosheets are added and ground evenly.

[0046] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0047] S1. After crushing and screening, the calcined petroleum coke is mixed with calcined petroleum coke and kneaded at 140℃ for 20 minutes. Molten coal tar pitch and additives are added and kneaded at 190℃ for 20 minutes. The mixture is then vibrated and molded for 1 minute at a vibration frequency of 30Hz. The temperature is maintained at 140℃ during the vibration process to obtain the green body.

[0048] S2. Cool the embryo to room temperature, raise the temperature to 400℃ at 20℃ / h, hold for 2h, continue to raise the temperature to 600℃, hold for 6h; seal, then raise the temperature to 1100℃ at 15℃ / h, hold for 20h, and cool to below 250℃.

[0049] Example 3

[0050] An antioxidant and corrosion resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives is 100:14.5:12:2.

[0051] Calcined petroleum coke comprises, by mass percentage: 37% coarse coke with a particle size of 5-10 mm, 34% medium coke with a particle size of 1-5 mm, and the remainder fine coke with a particle size of 0.1-1 mm.

[0052] The additive is prepared by the following specific operation: 12g of vapor-grown carbon fiber and 2.5g of activated nano-silica are added to 75g of graphite powder and mixed and ground evenly. Then, 4g of hexagonal boron nitride nanosheets are added and ground evenly.

[0053] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0054] S1. After crushing and screening, the calcined petroleum coke is mixed with calcined petroleum coke and kneaded at 148℃ for 13 minutes. Molten coal tar pitch and additives are added and kneaded at 198℃ for 12 minutes. The mixture is then vibrated and molded for 2.5 minutes at a vibration frequency of 22Hz. The temperature is maintained at 147℃ during the vibration process to obtain the green body.

[0055] S2. Cool the embryo to room temperature, raise the temperature to 480℃ at 25℃ / h, hold for 80 minutes, continue to raise the temperature to 750℃, hold for 3 hours; seal, then raise the temperature to 1020℃ at 20℃ / h, hold for 35 hours, and cool to below 250℃.

[0056] Example 4

[0057] An antioxidant and corrosion resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives is 100:14.9:8:4.

[0058] Calcined petroleum coke comprises, by mass percentage: 33% coarse coke with a particle size of 5-10 mm, 38% medium coke with a particle size of 1-5 mm, and the remainder fine coke with a particle size of 0.1-1 mm.

[0059] The additive is prepared by the following specific operation: 18g of vapor-grown carbon fiber and 1.5g of activated nano-silica are added to 65g of graphite powder and mixed and ground evenly. Then, 8g of hexagonal boron nitride nanosheets are added and ground evenly.

[0060] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0061] S1. After crushing and screening, the calcined petroleum coke is mixed with calcined petroleum coke and kneaded at 142℃ for 17 minutes. Molten coal tar pitch and additives are added and kneaded at 192℃ for 18 minutes. The mixture is then vibrated and molded for 1.5 minutes at a vibration frequency of 28 Hz. The temperature is maintained at 143℃ during the vibration process to obtain the green body.

[0062] S2. Cool the embryo to room temperature, raise the temperature to 420℃ at 30℃ / h, hold for 100min, continue to raise the temperature to 650℃, hold for 5h; seal, then raise the temperature to 1080℃ at 15℃ / h, hold for 25h, and cool to below 250℃.

[0063] Example 5

[0064] An antioxidant and corrosion-resistant prebaked anode (such as Figure 1 As shown in the figure, its raw materials include: calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives, and the mass ratio of calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives is 100:14.7:10:3.

[0065] Calcined petroleum coke comprises, by mass percentage: 35% coarse coke with a particle size of 5-10 mm, 35% medium coke with a particle size of 1-5 mm, and the remainder is fine coke with a particle size of 0.1-1 mm.

[0066] The additive is prepared by the following specific operation: 15g of vapor-grown carbon fiber and 2g of activated nano-silica are added to 70g of graphite powder and mixed and ground evenly. Then, 6g of hexagonal boron nitride nanosheets are added and ground evenly.

[0067] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0068] S1. After crushing and screening, obtain particles with a particle size of 1-15mm, mix with calcined petroleum coke, knead at 145℃ for 15min, add molten coal tar pitch and additives, knead at 195℃ for 15min, vibrate and shape for 2min, vibration frequency is 25Hz, and the temperature is maintained at 145℃ during vibration to obtain green blank.

[0069] S2. Cool the embryo to room temperature, raise the temperature to 450℃ at 25℃ / h, hold for 1.5h, continue to raise the temperature to 700℃, hold for 4h; seal, then raise the temperature to 1050℃ at 20℃ / h, hold for 30h, and cool to below 250℃.

[0070] Example 6

[0071] An antioxidant and corrosion-resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined granules, silica sol and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined granules, silica sol and additives is 100:14.7:10:1.3:3.

[0072] Calcined petroleum coke comprises, by mass percentage: 35% coarse coke with a particle size of 5-10 mm, 35% medium coke with a particle size of 1-5 mm, and the remainder is fine coke with a particle size of 0.1-1 mm.

[0073] The additive is prepared by the following specific operation: 15g of vapor-grown carbon fiber and 2g of activated nano-silica are added to 70g of graphite powder and mixed and ground evenly. Then, 6g of hexagonal boron nitride nanosheets are added and ground evenly.

[0074] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0075] S1. After crushing and screening, granules with a particle size of 1-15mm are obtained. The surface of the granules is sprayed with an ethanol aqueous solution containing silica sol (where the mass fraction of silica in the ethanol aqueous solution is 10% and the mass fraction of ethanol in the ethanol aqueous solution is 50%). Then, it is mixed with calcined petroleum coke and kneaded at 145℃ for 15min. Molten coal tar pitch and additives are added and kneaded at 195℃ for 15min. The mixture is then vibrated and molded for 2min at a vibration frequency of 25Hz. The temperature is maintained at 145℃ during the vibration process to obtain a green body.

[0076] S2. Cool the embryo to room temperature, raise the temperature to 450℃ at 25℃ / h, hold for 1.5h, continue to raise the temperature to 700℃, hold for 4h; seal, then raise the temperature to 1050℃ at 20℃ / h, hold for 30h, and cool to below 250℃.

[0077] Comparative Example 1

[0078] An antioxidant and corrosion-resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined granules, silica sol, additives, and hexagonal boron nitride nanosheets, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined granules, silica sol, additives, and hexagonal boron nitride nanosheets is 100:14.7:10:1.3:2.81:0.19.

[0079] Calcined petroleum coke comprises, by mass percentage: 35% coarse coke with a particle size of 5-10 mm, 35% medium coke with a particle size of 1-5 mm, and the remainder is fine coke with a particle size of 0.1-1 mm.

[0080] The additive is prepared by the following specific operation: 15g of vapor-grown carbon fiber and 2g of activated nano-silica are added to 70g of graphite powder and mixed and ground evenly.

[0081] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0082] S1. After crushing and screening, granules with a particle size of 1-15mm are obtained. The surface of the granules is sprayed with an ethanol aqueous solution containing silica sol (where the mass fraction of silica in the ethanol aqueous solution containing silica sol is 10% and the mass fraction of ethanol in the ethanol aqueous solution is 50%). Then, it is mixed with calcined petroleum coke and kneaded at 145℃ for 15min. Molten coal tar pitch, additives, and hexagonal boron nitride nanosheets are added and kneaded at 195℃ for 15min. The mixture is then vibrated and molded for 2min at a vibration frequency of 25Hz. The temperature is maintained at 145℃ during the vibration process to obtain a green body.

[0083] S2. Cool the embryo to room temperature, raise the temperature to 450℃ at 25℃ / h, hold for 1.5h, continue to raise the temperature to 700℃, hold for 4h; seal, then raise the temperature to 1050℃ at 20℃ / h, hold for 30h, and cool to below 250℃.

[0084] Comparative Example 2

[0085] An antioxidant and corrosion-resistant prebaked anode, the raw materials of which include: calcined petroleum coke, coal tar pitch, calcined granules, silica sol and additives, wherein the mass ratio of calcined petroleum coke, coal tar pitch, calcined granules, silica sol and additives is 100:14.7:10:1.3:3.

[0086] Calcined petroleum coke comprises, by mass percentage: 35% coarse coke with a particle size of 5-10 mm, 35% medium coke with a particle size of 1-5 mm, and the remainder is fine coke with a particle size of 0.1-1 mm.

[0087] The additive is prepared by the following specific operation: 15g of vapor-grown carbon fiber is added to 70g of graphite powder and mixed and ground evenly, and then 6g of hexagonal boron nitride nanosheets are added and ground evenly.

[0088] The preparation method of the above-mentioned antioxidant and corrosion-resistant prebaked anode includes the following steps:

[0089] S1. After crushing and screening, granules with a particle size of 1-15mm are obtained. The surface of the granules is sprayed with an ethanol aqueous solution containing silica sol (where the mass fraction of silica in the ethanol aqueous solution is 10% and the mass fraction of ethanol in the ethanol aqueous solution is 50%). Then, it is mixed with calcined petroleum coke and kneaded at 145℃ for 15min. Molten coal tar pitch and additives are added and kneaded at 195℃ for 15min. The mixture is then vibrated and molded for 2min at a vibration frequency of 25Hz. The temperature is maintained at 145℃ during the vibration process to obtain a green body.

[0090] S2. Cool the embryo to room temperature, raise the temperature to 450℃ at 25℃ / h, hold for 1.5h, continue to raise the temperature to 700℃, hold for 4h; seal, then raise the temperature to 1050℃ at 20℃ / h, hold for 30h, and cool to below 250℃.

[0091] The apparent density of the prebaked anodes obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 was determined in accordance with YS / T 63.7-2024 "Test Methods for Carbon Materials for Aluminum - Part 7: Determination of Apparent Density by Dimensional Method".

[0092] The true density of the prebaked anodes obtained in Examples 5, 6, 1, and 2 were determined in accordance with YS / T 63.9-2012 "Test Methods for Carbon Materials for Aluminum - Part 9: Determination of True Density by Helium Hydrometer Method".

[0093] The room temperature resistivity of the prebaked anodes obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 was determined in accordance with YS / T 63.2-2023 "Test Methods for Carbon Materials for Aluminum - Part 2: Determination of Room Temperature Resistivity".

[0094] The compressive strength of the prebaked anodes obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 was determined in accordance with YS / T 63.15-2023 "Test Methods for Carbon Materials for Aluminum - Part 15: Determination of Compressive Strength".

[0095] The residual air reactivity of the prebaked anodes obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 was determined in accordance with YS / T 63.11-2024 "Test Methods for Carbon Materials for Aluminum - Part 11: Determination of Air Reactivity".

[0096] The air permeability of the prebaked anodes obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 was determined in accordance with YS / T 63.10-2012 "Test Methods for Carbon Materials for Aluminum - Part 10: Determination of Air Permeability".

[0097] like Figures 2 to 4As shown, the prebaked anode obtained in Example 6 has the lowest room temperature resistivity and air permeability, and the highest pressure resistance and air reaction residue rate, which are superior to Example 5 and Comparative Examples 1-2 (P < 0.05); while the apparent density and true density of the prebaked anode obtained in Example 6 are both lower than those of Example 5 and Comparative Examples 1-2, but there is no significant difference (P > 0.05).

[0098] The reason for the above results is that this invention uses a three-dimensional conductive framework formed by high aspect ratio vapor-grown carbon fibers and layered graphite powder to create a continuous conductive pathway in the matrix. This not only provides excellent stability but also significantly reduces the electron transport barrier through a multi-scale conductive network. Simultaneously, nano-silica fills the pores, reducing electron scattering and greatly lowering the resistivity. This invention utilizes the synergistic effect of a silica sol coating layer and hexagonal boron nitride nanosheets to achieve a dual improvement in density and oxidation resistance. After heat treatment, the silica sol forms an amorphous SiO2 protective layer, effectively sealing the surface pores of the carbon matrix and blocking the oxygen diffusion path. Meanwhile, the layered structure of the hexagonal boron nitride nanosheets interspersed between the graphite layers effectively reduces microcrack formation by inhibiting interlayer slippage. Furthermore, its chemical inertness delays the carbon-oxygen reaction. The combined effect of these two factors improves density while effectively shortening the oxygen ion diffusion path.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An antioxidant and corrosion-resistant prebaked anode, characterized in that, Its raw materials include: calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives, with the mass ratio of calcined petroleum coke, coal tar pitch, calcined coal tar pitch and additives being 100:14.2-15.2:5-15:1-5; The raw materials of the additive include, by mass, 60-80 parts of graphite powder, 10-20 parts of vapor-grown carbon fiber, 1-3 parts of activated nano-silica, and 1-10 parts of hexagonal boron nitride nanosheets. The additive is prepared by the following specific operation: adding vapor-grown carbon fiber and activated nano-silica to graphite powder, mixing and grinding evenly, and then adding hexagonal boron nitride nanosheets and grinding evenly. The prebaked anode is prepared by mixing crushed and calcined petroleum coke at 140-150℃ for 10-20 minutes, adding molten coal tar pitch and additives, mixing at 190-200℃ for 10-20 minutes, forming by high-temperature vibration, cooling, heating to 400-500℃ and holding for 1-2 hours, continuing to heat to 600-800℃ and holding for 2-6 hours; sealing, then heating to 1000-1100℃ and holding for 20-40 hours, and finally cooling.

2. The antioxidant and corrosion-resistant prebaked anode according to claim 1, characterized in that, The antioxidant and corrosion resistant prebaked anode has a room temperature resistivity ≤56μΩ•m and a withstand voltage strength ≥42.7MPa.

3. The antioxidant and corrosion-resistant prebaked anode according to claim 1, characterized in that, The softening point of the coal tar pitch is 105-115℃, and the coking value is 54-58%.

4. The antioxidant and corrosion-resistant prebaked anode according to claim 1, characterized in that, Calcined petroleum coke includes: coarse coke with a particle size of 5-10 mm, medium coke with a particle size of 1-5 mm, and fine coke with a particle size of 0.1-1 mm; the coarse coke accounts for 30-40% of the mass percentage of calcined petroleum coke, the medium coke accounts for 30-40% of the mass percentage of calcined petroleum coke, and the remainder is fine coke.

5. The antioxidant and corrosion-resistant prebaked anode according to claim 1, characterized in that, The activated nano-silica is nano-silica activated by silane coupling agent KH550.

6. The antioxidant and corrosion-resistant prebaked anode according to claim 1, characterized in that, The graphite powder has a particle size D50 of 5 μm; the activated nano-silica has a particle size of 20-50 nm; and the vapor-grown carbon fiber has a diameter of 50-150 nm and an aspect ratio of 25-35.

7. The antioxidant and corrosion-resistant prebaked anode according to claim 1, characterized in that, Its raw materials also include: silica sol, with a mass ratio of silica sol to calcined silica sol of 0.05-0.2:1; The cooked and crushed material is first processed as follows: after being crushed, it is sieved, and its surface is sprayed with an ethanol aqueous solution containing silica sol, and then heat-treated at 300-400℃ for 10-30 minutes.

8. A method for preparing an antioxidant and corrosion-resistant prebaked anode as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. After crushing the calcined coal tar pitch, sieve it and mix it with calcined petroleum coke. Knead it at 140-150℃ for 10-20 minutes. Add the molten coal tar pitch and additives and knead it at 190-200℃ for 10-20 minutes. Vibrate it for 1-3 minutes at a vibration frequency of 20-30Hz. Keep the temperature at 140-150℃ during the vibration process to obtain the green body. S2. Cool the embryo to room temperature, raise the temperature to 400-500℃ at 15-30℃ / h, hold for 1-2 hours, continue to raise the temperature to 600-800℃, hold for 2-6 hours; seal, then raise the temperature to 1000-1100℃ at 10-20℃ / h, hold for 20-40 hours, and cool to below 250℃.

9. A method for preparing the antioxidant and corrosion-resistant prebaked anode as described in claim 7, characterized in that, Includes the following steps: S1. After crushing the calcined coal, sieve it and spray an ethanol-water solution containing silica sol onto its surface. Heat treat it at 300-400℃ for 10-30 minutes. Then mix it with calcined petroleum coke and knead it at 140-150℃ for 10-20 minutes. Add molten coal tar pitch and additives and knead it at 190-200℃ for 10-20 minutes. Vibrate it for 1-3 minutes at a vibration frequency of 20-30Hz. Maintain the temperature at 140-150℃ during the vibration process to obtain a green body. S2. Cool the embryo to room temperature, raise the temperature to 400-500℃ at 15-30℃ / h, hold for 1-2 hours, continue to raise the temperature to 600-800℃, hold for 2-6 hours; seal, then raise the temperature to 1000-1100℃ at 10-20℃ / h, hold for 20-40 hours, and cool to below 250℃.

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