High-compressive-strength prebaked anode and production process thereof

Abstract

The invention provides a prebaked anode with high compressive strength. The prebaked anode comprises the following raw materials: 68-85 parts by mass of calcined petroleum coke particles; 12-25 parts by mass of a modified coal pitch binder, wherein the softening point of the modified coal pitch binder is 105-115 DEG C; and 0.3-0.8 part by mass of a whisker reinforcing agent. The production process comprises the following steps: calcining, crushing and grading, modifying fine powder, preparing a binder, mixing and kneading, forming and roasting. The prebaked anode has the advantages that through multi-stage material collaboration and process innovation, under the condition that an existing production line is not changed at all, the core contradictions that the prebaked anode is insufficient in strength, poor in conductivity and poor in high-temperature stability are synchronously solved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a prebaked anode with high compressive strength and a production process thereof. Background Art

[0002] Prebaked anodes, core components of aluminum electrolytic cells, are made from a carbon material calcined at high temperatures using petroleum coke as the aggregate and coal tar as the binder. Their performance directly determines the current efficiency and energy consumption of electrolytic aluminum production. In modern, large-scale prebaked electrolytic cells, operating currents typically range from 160 to 500 kA, and the anodes must continuously withstand temperatures of 950°C and mechanical loads of 0.8 to 1.2 MPa. These demanding operating conditions place high demands on the anode's mechanical strength, electrical conductivity, and thermal stability.

[0003] However, existing commercial pre-baked anode products face three key technical defects: First, the interfacial bonding strength between petroleum coke particles and coal tar pitch is insufficient. During the roasting process, the difference in thermal expansion coefficients between the two generates thermal stress concentration, which causes microcracks to initiate and expand, causing the product's compressive strength to remain at 32-35MPa for a long time, and frequent edge fracture accidents during the electrolytic cell startup phase. Secondly, the aggregate grading design in the traditional formula ignores the effect of fine powder activity. The filling rate of fine powder with a particle size of less than 1mm is less than 40%, which not only reduces the product's volume density to 1.52-1.55g / cm³, but also exacerbates high-temperature creep. Under continuous load at 900℃, the anode deformation rate exceeds 2×10⁻ 4 s⁻¹, causing an imbalance in the electrolytic cell's current distribution. Third, existing enhancement and modification technologies present significant performance tradeoffs. For example, while adding carbon nanotubes can increase compressive strength by 20%, the viscosity-increasing effect increases kneading energy consumption by 35%, while also reducing the green anode forming qualification rate. Furthermore, the incorporation of silicon micropowder, due to its insulating properties, increases resistivity to over 65μΩ·m, significantly exceeding the industry safety threshold of 60μΩ·m.

[0004] To address these challenges, recent technological developments have focused on two main areas: Regarding material composition, some have attempted to use boron carbide-modified asphalt binders. However, this modifier increases the cost by 120,000 yuan per ton and requires an increase in kneading temperature above 190°C, resulting in an 8% increase in coal tar coking. Research has employed gradation optimization to adjust the coarse-to-medium particle ratio to 2.6:2.0. However, due to the presence of oxygen functional groups on the surface of untreated fine powder, gas release channels are generated during the calcination stage, forming closed pores with diameters exceeding 50 μm. Regarding process improvements, a multi-stage kneading process has been designed, but the temperature control accuracy required is ±1°C, making implementation extremely challenging. Others have proposed ultra-high-temperature calcination above 1150°C, which, while increasing strength by 3 MPa, doubles energy consumption. These technical solutions have failed to overcome the triple bottlenecks of weak interfacial bonding, the mutually exclusive strength / conductivity trade-off, and high process costs, forcing aluminum smelters to incur tens of millions of yuan in additional annual anode replacement and power losses. Therefore, the development of a high-compressive-strength prebaked anode and its production process are crucial. Summary of the Invention

[0005] In order to overcome the defects in the prior art, a high compressive strength prebaked anode and a production process thereof are provided.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A prebaked anode with high compressive strength, comprising the following raw materials:

[0008] 68-85 parts by mass of calcined petroleum coke particles;

[0009] 12-25 parts by mass of a modified coal tar binder, wherein the softening point of the modified coal tar binder is 105-115°C;

[0010] Whisker reinforcement 0.3-0.8 parts by mass

[0011] The calcined petroleum coke particles include coarse particles with a particle size of 4-8 mm, medium particles with a particle size of 1-4 mm, and fine powder with a particle size of less than 1 mm. The mass ratio of the coarse particles, medium particles, and fine powder is (3.5-4.5): (2.8-3.5): (2.5-3.2).

[0012] The modified coal tar binder is prepared by the following steps:

[0013] a) Place coal tar pitch with a softening point of 82-86°C in a reactor and heat it to 160-170°C at a rate of 3-5°C / min in a nitrogen atmosphere;

[0014] b) adding nano-silicon carbide powder equivalent to 5-8% by mass of coal tar pitch, with an average particle size of 50 nm;

[0015] c) maintaining stirring at 800-1200 rpm for 40-60 minutes;

[0016] d) Cooling to room temperature forms a solid binder, which is the modified coal tar binder.

[0017] The nano-silicon carbide powder is pre-treated as follows: the nano-silicon carbide powder is immersed in a hydrofluoric acid solution with a mass concentration of 15% for 2 hours; then washed with deionized water until the pH value of the filtrate is 6.5-7.5; and vacuum dried at 120° C. for 2 hours.

[0018] The calcined petroleum coke fine powder is subjected to plasma modification, and the modification process comprises the following steps: placing the fine powder in a radio frequency plasma equipment cavity, introducing argon gas to stabilize the gas pressure at 0.5-0.8 Pa; applying 30 kW radio frequency power for 15-30 minutes to obtain modified fine powder, wherein the surface oxygen content of the modified fine powder obtained after plasma modification is reduced to 5-7wt%.

[0019] The whisker reinforcement comprises aluminum borate whiskers and potassium titanate whiskers, and the mass ratio of the aluminum borate whiskers to the potassium titanate whiskers is 1:0.6-1.2;

[0020] The diameter of the aluminum borate whisker is 0.5-1 μm, and the aspect ratio is 30-50; the diameter of the potassium titanate whisker is 0.2-0.5 μm, and the aspect ratio is 40-60.

[0021] A production process for a prebaked anode with high compressive strength, comprising the following steps:

[0022] (1) Calcination process: petroleum coke is loaded into a pot calciner and calcined at 1250-1350°C for 28-32 hours to obtain calcined petroleum coke;

[0023] (2) Crushing and grading: The calcined petroleum coke is processed by a crusher and sieved to obtain coarse particles of 4-8 mm, medium particles of 1-4 mm, and fine powder less than 1 mm;

[0024] (3) Powder modification: The fine powder obtained in step (2) is subjected to plasma modification to obtain modified fine powder;

[0025] (4) Binder preparation: preparation of modified coal tar binder;

[0026] (5) Kneading: The coarse particles and medium particles obtained in step (2), the modified fine powder obtained in step (3), the binder obtained in step (4), and the whisker reinforcing agent are placed in a kneader and kneaded at 160-175° C. for 25-40 minutes;

[0027] (6) Molding: The mixed material is placed into a mold and vibrated under a pressure of 30-45 MPa to form a green anode;

[0028] (7) Calcination: Place the green anode in a ring calcination furnace, heat it to 1100-1200℃ at 15-20℃ / hour, and keep it at this temperature for 24-36 hours.

[0029] Step (5) kneading is carried out in stages: first, coarse particles and medium particles are added and kneaded for 8-12 minutes; then, zinc stearate equivalent to 0.1-0.3% of the total raw material mass is added as a lubricant; finally, the modified fine powder, binder and whisker reinforcement are added and kneaded for 17-28 minutes.

[0030] In step (7), when the temperature is in the range of 350-550°C, the heating rate is controlled to be 2-3°C / min, and inert gas is used for rapid cooling at the end of roasting, and the cooling rate is not less than 50°C / min.

[0031] In step (6), the frequency of vibration molding is 40-50 Hz, and the amplitude is 0.8-1.2 mm.

[0032] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0033] 1. The pre-baked anode technology solution of this application improves overall performance through multiple synergistic mechanisms. In terms of the bonding system, a coal tar binder modified with nano-silicon carbide is used, so that the nanoparticles are embedded in the asphalt molecular chains in a high-temperature molten state, forming a three-dimensional reinforced network. This structure significantly enhances the rigidity of the bonding phase itself. More importantly, during the subsequent baking process, the modified binder can more fully infiltrate the surface of the petroleum coke particles, effectively suppressing the initiation of microcracks caused by differences in thermal expansion coefficients by enhancing interfacial chemical bonding.

[0034] 2. For the fine powder component of the aggregate system, a plasma surface activation treatment is specifically introduced. This process uses high-energy argon ion bombardment to selectively remove low-reactive oxygen-containing groups on the fine powder surface, while simultaneously generating a large number of dangling bonds. These activated sites interact strongly with the liquid binder during the mixing stage, transforming fine powder regions prone to defects in traditional processes into high-strength connection points, significantly enhancing the functional contribution of the fine powder to the system.

[0035] 3. The design of a whisker reinforcement compound resolves the performance contradictions of traditional single reinforcement materials. Aluminum borate whiskers provide skeletal support through their high modulus, while potassium titanate whiskers maintain the conductive network through their unique ion-conducting pathways. When used synergistically in a specific ratio, the two form an interpenetrating reinforcement structure within the matrix, which withstands mechanical stress while ensuring efficient electron transmission, avoiding the resistivity degradation caused by the introduction of reinforcements.

[0036] 4. The innovative staged mixing process significantly optimizes dispersion. Initially, only coarse and medium particles are dry-mixed to eliminate interstitial pores between large particles before the binder and fine powder are introduced. This sequential design ensures that the fine powder fully fills the interstices within the framework. A specially added trace lubricant, introduced in the final stages of mixing, precisely reduces system viscosity, preventing whisker breakage due to excessive friction and maintaining the integrity of the reinforcement phase.

[0037] 5. The gradient temperature control strategy during the roasting phase of this application is crucial to product performance. A reduced temperature ramp is implemented within the critical temperature range for asphalt decomposition to ensure the orderly release of volatiles and eliminate internal porosity defects. The rapid cooling process rapidly freezes the microstructure, locking in the ideal bond between whiskers and aggregate, resulting in a more balanced internal stress distribution. DETAILED DESCRIPTION

[0038] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0039] In this application, the sources of various raw materials are briefly described as follows:

[0040] 1. Petroleum coke

[0041] Purchasing manufacturer: PetroChina Liaoyang Petrochemical Company Specifications: Meet the first-level standard of YS / T 587-2020, sulfur content ≤1.8%, volatile matter ≤0.5%

[0042] 2. Coal tar

[0043] Purchaser: Shanxi Hongte Coal Chemical Co., Ltd. Model: HT-MZ86, softening point 82-86℃, toluene insoluble matter 26-30%

[0044] 3. Nano-silicon carbide powder

[0045] Purchasing manufacturer: Anhui Yishitong Materials Technology Co., Ltd. Model: EShine-SC50, average particle size 50±5nm, purity>99.9%, CAS No. 409-21-2

[0046] 4. Hydrofluoric acid

[0047] Purchasing manufacturer: Duofuduo New Materials Co., Ltd.

[0048] Model: PEDF-40, 40% stock solution, CAS No. 7664-39-3 (need to dilute to 15%)

[0049] 5. Argon (high purity)

[0050] Purchasing manufacturer: Hangzhou Hangyang Co., Ltd.

[0051] Model: GY-ArG5, purity ≥99.999%, in compliance with GB / T 4842-2017

[0052] 6. Aluminum borate whiskers

[0053] Purchasing manufacturer: Jiangsu Huachi Functional Materials Co., Ltd.

[0054] Model: HC-ABW80, diameter 0.5-1μm, aspect ratio 35-50, CAS No. 12041-78-2

[0055] 7. Potassium titanate whiskers

[0056] Purchasing manufacturer: Shandong Jingxin Electronic Materials Co., Ltd.

[0057] Model: JX-TKW120, diameter 0.2-0.5μm, aspect ratio 45-60, CAS No. 12056-50-3

[0058] 8. Zinc stearate

[0059] Purchasing manufacturer: Nanjing Chemical Reagent Co., Ltd.

[0060] Model: C70053, zinc content 10-11%, CAS No. 557-05-1

[0061] A prebaked anode with high compressive strength, comprising the following raw materials:

[0062] 68-85 parts by mass of calcined petroleum coke particles;

[0063] 12-25 parts by mass of a modified coal tar binder, wherein the softening point of the modified coal tar binder is 105-115°C;

[0064] Whisker reinforcement 0.3-0.8 parts by mass

[0065] The calcined petroleum coke particles include coarse particles with a particle size of 4-8 mm, medium particles with a particle size of 1-4 mm, and fine powder with a particle size of less than 1 mm. The mass ratio of the coarse particles, medium particles, and fine powder is (3.5-4.5): (2.8-3.5): (2.5-3.2).

[0066] The modified coal tar binder is prepared by the following steps:

[0067] a) Place coal tar pitch with a softening point of 82-86°C in a reactor and heat it to 160-170°C at a rate of 3-5°C / min in a nitrogen atmosphere;

[0068] b) adding nano-silicon carbide powder equivalent to 5-8% by mass of coal tar pitch, with an average particle size of 50 nm;

[0069] c) maintaining stirring at 800-1200 rpm for 40-60 minutes;

[0070] d) Cooling to room temperature forms a solid binder, which is the modified coal tar binder.

[0071] The nano-silicon carbide powder is pre-treated as follows: the nano-silicon carbide powder is immersed in a hydrofluoric acid solution with a mass concentration of 15% for 2 hours; then washed with deionized water until the pH value of the filtrate is 6.5-7.5; and vacuum dried at 120° C. for 2 hours.

[0072] The calcined petroleum coke fine powder is subjected to plasma modification, and the modification process comprises the following steps: placing the fine powder in a radio frequency plasma equipment cavity, introducing argon gas to stabilize the gas pressure at 0.5-0.8 Pa; applying 30 kW radio frequency power for 15-30 minutes to obtain modified fine powder, wherein the surface oxygen content of the modified fine powder obtained after plasma modification is reduced to 5-7wt%.

[0073] The whisker reinforcement comprises aluminum borate whiskers and potassium titanate whiskers, and the mass ratio of the aluminum borate whiskers to the potassium titanate whiskers is 1:0.6-1.2;

[0074] The diameter of the aluminum borate whisker is 0.5-1 μm, and the aspect ratio is 30-50; the diameter of the potassium titanate whisker is 0.2-0.5 μm, and the aspect ratio is 40-60.

[0075] A production process for a prebaked anode with high compressive strength, comprising the following steps:

[0076] (1) Calcination process: petroleum coke is loaded into a pot calciner and calcined at 1250-1350°C for 28-32 hours to obtain calcined petroleum coke;

[0077] (2) Crushing and grading: The calcined petroleum coke is processed by a crusher and sieved to obtain coarse particles of 4-8 mm, medium particles of 1-4 mm, and fine powder less than 1 mm;

[0078] (3) Powder modification: The fine powder obtained in step (2) is subjected to plasma modification to obtain modified fine powder;

[0079] (4) Binder preparation: preparation of modified coal tar binder;

[0080] (5) Kneading: The coarse particles and medium particles obtained in step (2), the modified fine powder obtained in step (3), the binder obtained in step (4), and the whisker reinforcing agent are placed in a kneader and kneaded at 160-175° C. for 25-40 minutes;

[0081] (6) Molding: The mixed material is placed into a mold and vibrated under a pressure of 30-45 MPa to form a green anode;

[0082] (7) Calcination: Place the green anode in a ring calcination furnace, heat it to 1100-1200℃ at 15-20℃ / hour, and keep it at this temperature for 24-36 hours.

[0083] Step (5) kneading is carried out in stages: first, coarse particles and medium particles are added and kneaded for 8-12 minutes; then, zinc stearate equivalent to 0.1-0.3% of the total raw material mass is added as a lubricant; finally, the modified fine powder, binder and whisker reinforcement are added and kneaded for 17-28 minutes.

[0084] In step (7), when the temperature is in the range of 350-550°C, the heating rate is controlled to be 2-3°C / min, and inert gas is used for rapid cooling at the end of roasting, and the cooling rate is not less than 50°C / min.

[0085] In step (6), the frequency of vibration molding is 40-50 Hz, and the amplitude is 0.8-1.2 mm.

[0086] The innovation of this application lies in that, for the first time, a three-level synergistic mechanism of nano-silicon carbide confinement enhancement, plasma selective etching to activate aggregate, and double whisker compounding to conduct stress / current simultaneously solves the core contradictions that have long existed in the field of pre-baked anodes, namely weak interface bonding, mutual exclusion of strength / conductivity, and poor process adaptability. Specifically, hydrofluoric acid-activated nano-silicon carbide is used to construct a spatial confinement structure in coal tar pitch, and the Si-OC covalent bond is used to increase the softening point of the binder by 30% and strengthen the interface bonding; argon plasma high-energy bombardment is used to selectively remove oxygen-containing groups on the surface of fine powder, thereby increasing the surface energy of the aggregate by 50% and achieving molecular-level wetting; an innovative design of an interpenetrating network of aluminum borate / potassium titanate whiskers decouples and synergizes the high modulus skeleton and ion conductive channels, breaking through the 38MPa compressive strength threshold while ensuring a conductivity of ≤53μΩ·m; combined with segmented kneading dynamics control and precise control of calcination phase transition, the high-temperature creep rate is reduced by 44% and compatible with existing production lines, ultimately achieving a dual breakthrough in material performance and industrial production.

[0087] The technical solution of the present invention is further illustrated by the following examples and comparative examples, but the protection scope of the present invention is not limited thereto.

[0088] Example 1

[0089] The process for preparing high-compressive-strength prebaked anodes is as follows: First, 78 parts by mass of petroleum coke is charged into a pot calciner and calcined at 1300°C for 30 hours to obtain calcined petroleum coke. The calcined petroleum coke is then crushed and sieved to produce coarse particles (4-8 mm), medium particles (1-4 mm), and fine powder (<1 mm) in a mass ratio of 4.5:2.8:2.5. The fine powder is then placed in an RF plasma system, treated with argon gas at a pressure of 0.6 Pa and a power of 30 kW for 22 minutes to obtain a modified fine powder with a surface oxygen content of 6 wt%.

[0090] Preparation of modified coal tar binder: Take coal tar with a softening point of 82℃, heat it to 160℃ at 3℃ / min, add nano-silicon carbide powder equivalent to 8% of the mass of coal tar (previously impregnated with 15% hydrofluoric acid for 2 hours, washed with deionized water to pH 6.5, and vacuum dried at 120℃), stir at 800rpm for 60 minutes, and cool to obtain a binder with a softening point of 115℃.

[0091] Kneading process: Coarse and medium granules were first dry-mixed in a kneader for 12 minutes. Zinc stearate lubricant (0.1% of the total raw materials) was added. Then, modified fine powder, 25 parts binder, and 0.8 parts whisker reinforcement (aluminum borate whiskers and potassium titanate whiskers in a ratio of 1:0.6, with aluminum borate having a diameter of 1 μm and an aspect ratio of 30, and potassium titanate having a diameter of 0.5 μm and an aspect ratio of 40) were added. Kneading was continued at 175°C for 17 minutes. Vibration molding parameters included a pressure of 45 MPa, a frequency of 40 Hz, and an amplitude of 1.2 mm. Calcination was performed at a temperature increase of 20°C / h, with a controlled rate of 2°C / min before reaching 550°C. The temperature was then maintained at 1200°C for 24 hours, followed by an argon quench at a rate of 50°C / min.

[0092] Example 2

[0093] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0094] 68 parts of petroleum coke were calcined at 1250°C for 32 hours. The crushed particles were sized in a ratio of 3.5:3.5:3.2. The fine powder was treated at 0.5 Pa pressure and 30 kW for 30 minutes, resulting in a surface oxygen content of 7 wt%.

[0095] Preparation of binder: Coal tar pitch with a softening point of 86°C was heated to 170°C at a rate of 5°C / min, 5% pretreated nano-silicon carbide (washing water pH 7.5) was added, and stirred at 1200 rpm for 40 minutes to obtain 12 parts of a binder with a softening point of 105°C.

[0096] Kneading: Knead the coarse and medium particles for 10 minutes; add 0.2% zinc stearate; add the modified fine powder, binder, and 0.55 parts of whisker reinforcement (whisker ratio 1:0.9, aluminum borate diameter 0.7μm / aspect ratio 40, potassium titanate diameter 0.3μm / aspect ratio 50), and knead at 168°C for 22 minutes. Molding pressure 38MPa, frequency 45Hz, amplitude 1.0mm. Calcination temperature rise 18°C / h, control speed 2.5°C / min before 450°C, hold at 1150°C for 30 hours, and quench at 55°C / min.

[0097] Example 3

[0098] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0099] 85 parts of petroleum coke were calcined at 1350°C for 28 hours. The particle size ratio was 4.0:3.0:2.8. The fine powder was treated at 0.8 Pa and 30 kW for 15 minutes, and the surface oxygen content was 5 wt%.

[0100] Binder: Coal tar with a softening point of 84°C was heated to 165°C at a rate of 4°C / min, 6.5% nano-silicon carbide (pH 7.0) was added, and stirred at 1000 rpm for 50 minutes to obtain 19 parts of a binder with a softening point of 110°C.

[0101] Kneading: Coarse and medium particles were first kneaded for 8 minutes; 0.3% zinc stearate was added; then the modified fine powder, binder, and 0.3 parts of whisker reinforcement (aluminum borate to potassium titanate whisker ratio of 1:1.2, aluminum borate diameter 0.5μm / aspect ratio 50, potassium titanate diameter 0.2μm / aspect ratio 60) were added. Kneading was continued at 160°C for 28 minutes. Molding pressure was 30MPa, frequency 50Hz, and amplitude 0.8mm. Calcination temperature was increased at 15°C / h, controlled at 3°C / min before reaching 350°C, held at 1100°C for 36 hours, and quenched at 60°C / min.

[0102] Comparative Example 1

[0103] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0104] Except that the binder was changed to unmodified coal tar (softening point 86°C).

[0105] Comparative Example 2

[0106] In this comparative example, the same points as Example 2 are not repeated here, and the differences are as follows:

[0107] The fine powder was not plasma treated (surface oxygen content 12 wt%).

[0108] Comparative Example 3

[0109] In this comparative example, the same points as in Example 3 are not repeated here, and the differences are as follows:

[0110] The whisker reinforcement used was aluminum borate whisker only (0.8 parts).

[0111] Comparative Example 4

[0112] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0113] The kneading was not segmented, and all the raw materials were put into the kneading for 40 minutes at a time.

[0114] Comparative Example 5

[0115] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0116] During calcination, the temperature was raised in the range of 350-550°C at a conventional rate of 5°C / min.

[0117] Performance test results and analysis

[0118] The performance tests of the prebaked anodes of the embodiment and the comparative example were respectively conducted, wherein the compressive strength was tested according to GB / T 1431, the resistivity was measured according to GB / T 24525, and the high-temperature creep rate (900°C / 0.8 MPa) was measured according to GB / T 30067. The test results are shown in Table 1.

[0119] As can be seen in Table 1, Example 1, using the highest binder addition of 25 parts per million and a very large particle size ratio, achieved a maximum strength of 41.5 MPa. This is due to three mechanisms: nano-silicon carbide modification increases the shear strength of the binder-aggregate interface by approximately 40%, plasma treatment of fine powder increases the aggregate gap filling rate from the conventional 40% to 53%, and whiskers compounded into the matrix form a cross-scale reinforcement network. Compared to 33.1 MPa in Comparative Example 1, this demonstrates that the unmodified binder induces microcrack propagation due to weak interfacial bonding. The compressive strength data validate the synergistic effect of the technical solution.

[0120] Although Example 2 used a minimum binder dosage of 12 parts, the 1:1.2 ratio of aluminum borate to potassium titanate whiskers formed a dual ion-electron pathway, maintaining excellent conductivity of 52.7 μΩ·m. In contrast, in Comparative Example 2, the thickened oxygen-containing layer (12 wt%) on the surface of the untreated fine powder hindered electron migration, causing the resistance to rise sharply to 59.8 μΩ·m, demonstrating the repairing effect of plasma activation on the conductive pathway.

[0121] Table 1 Analysis and test results

[0122] Test indicators Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Compressive strength (MPa) 41.5 38.2 40.1 33.1 35.7 36.8 37.3 36.0 Resistivity (μΩ·m) 50.3 52.7 51.0 54.2 59.8 57.4 53.1 56.3 <![CDATA[Creep rate (×10⁻ 5 s⁻¹)]]> 1.8 2.1 1.9 3.9 3.2 2.8 2.5 3.4

[0123] Example 3 creep rate at 900℃ / 0.8MPa is 1.9×10⁻ 5 s⁻¹, compared with 3.4×10⁻ in comparative example 5 5 The 44% reduction in s⁻¹ is attributed to two key processes: a controlled heating rate of 350-550°C during the calcination phase reduces the peak volatile release by 28%, and a rapid cooling process reduces the internal residual stress from the conventional 14MPa to 6MPa. Although the single whisker system in Comparative Example 3 achieves a compressive strength of 36.8MPa, due to the lack of the stress-dispersing effect of potassium titanate whiskers, the creep rate data reflects a breakthrough in thermal stability, and high-temperature creep is still higher than that of the composite system.

[0124] Comparative Example 4, using single-stage kneading, maintained a compressive strength of 37.3 MPa, but 3.2% of the corners cracked during vibration molding. In contrast, Example 1's staged kneading, by first building a coarse particle skeleton and then introducing fine powder filling, increased the green density by 0.12 g / cm³ and achieved a molding pass rate exceeding 99.5%, demonstrating that the influence of the kneading process cannot be underestimated.

[0125] The test results show that the compressive strength of the embodiment exceeds 38MPa and the high temperature creep rate is lower than 2.1×10⁻ under the premise of maintaining the resistivity ≤53μΩ·m. 5 s⁻¹, simultaneously solving the three major problems in the background technology: weak interface bonding, mutual exclusion of performance, and poor process adaptability.

[0126] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A prebaked anode with high compressive strength, characterized in that: The prebaked anode includes the following raw materials: 68-85 parts by mass of calcined petroleum coke particles; 12-25 parts by mass of a modified coal tar binder, wherein the softening point of the modified coal tar binder is 105-115°C; Whisker reinforcement 0.3-0.8 parts by mass 2. The high compressive strength prebaked anode according to claim 1, characterized in that: The calcined petroleum coke particles include coarse particles with a particle size of 4-8 mm, medium particles with a particle size of 1-4 mm, and fine powder with a particle size of less than 1 mm. The mass ratio of the coarse particles, medium particles, and fine powder is (3.5-4.5): (2.8-3.5): (2.5-3.2).

3. The high compressive strength prebaked anode according to claim 1, characterized in that: The modified coal tar binder is prepared by the following steps: a) Place coal tar pitch with a softening point of 82-86°C in a reactor and heat it to 160-170°C at a rate of 3-5°C / min in a nitrogen atmosphere; b) adding nano-silicon carbide powder equivalent to 5-8% by mass of coal tar pitch, with an average particle size of 50 nm; c) maintaining stirring at 800-1200 rpm for 40-60 minutes; d) Cooling to room temperature forms a solid binder, which is the modified coal tar binder.

4. The high compressive strength prebaked anode according to claim 3, characterized in that: The nano-silicon carbide powder is pre-treated as follows: the nano-silicon carbide powder is immersed in a hydrofluoric acid solution with a mass concentration of 15% for 2 hours; then washed with deionized water until the pH value of the filtrate is 6.5-7.5; and vacuum dried at 120° C. for 2 hours.

5. The high compressive strength prebaked anode according to claim 1, characterized in that: The calcined petroleum coke fine powder is subjected to plasma modification, and the modification process comprises the following steps: placing the fine powder in a radio frequency plasma equipment cavity, introducing argon gas to stabilize the gas pressure at 0.5-0.8 Pa; applying 30 kW radio frequency power for 15-30 minutes to obtain modified fine powder, wherein the surface oxygen content of the modified fine powder obtained after plasma modification is reduced to 5-7wt%.

6. The high compressive strength prebaked anode according to claim 1, characterized in that: The whisker reinforcement comprises aluminum borate whiskers and potassium titanate whiskers, and the mass ratio of the aluminum borate whiskers to the potassium titanate whiskers is 1:0.6-1.2; The diameter of the aluminum borate whisker is 0.5-1 μm, and the aspect ratio is 30-50; the diameter of the potassium titanate whisker is 0.2-0.5 μm, and the aspect ratio is 40-60.

7. A process for producing a prebaked anode with high compressive strength according to any one of claims 1 to 6, characterized in that: The production process includes the following steps: (1) Calcination process: petroleum coke is loaded into a pot calciner and calcined at 1250-1350°C for 28-32 hours to obtain calcined petroleum coke; (2) Crushing and grading: The calcined petroleum coke is processed by a crusher and sieved to obtain coarse particles of 4-8 mm, medium particles of 1-4 mm, and fine powder less than 1 mm; (3) Powder modification: The fine powder obtained in step (2) is subjected to plasma modification to obtain modified fine powder; (4) Binder preparation: preparation of modified coal tar binder; (5) Kneading: The coarse particles and medium particles obtained in step (2), the modified fine powder obtained in step (3), the binder obtained in step (4), and the whisker reinforcing agent are placed in a kneader and kneaded at 160-175° C. for 25-40 minutes; (6) Molding: The mixed material is placed into a mold and vibrated under a pressure of 30-45 MPa to form a green anode; (7) Calcination: Place the green anode in a ring calcination furnace, heat it to 1100-1200℃ at 15-20℃ / hour, and keep it at this temperature for 24-36 hours.

8. The process for producing a prebaked anode with high compressive strength according to claim 7, characterized in that: Step (5) kneading is carried out in stages: first, coarse particles and medium particles are added and kneaded for 8-12 minutes; then, zinc stearate equivalent to 0.1-0.3% of the total raw material mass is added as a lubricant; finally, the modified fine powder, binder and whisker reinforcement are added and kneaded for 17-28 minutes.

9. The process for producing a prebaked anode with high compressive strength according to claim 7, characterized in that: In step (7), when the temperature is in the range of 350-550°C, the heating rate is controlled to be 2-3°C / min, and inert gas is used for rapid cooling at the end of roasting, and the cooling rate is not less than 50°C / min.

10. The process for producing a prebaked anode with high compressive strength according to claim 7, characterized in that: In step (6), the frequency of vibration molding is 40-50 Hz, and the amplitude is 0.8-1.2 mm.