CN118084493A - A graphite coke electrode for submerged arc furnace and its preparation process - Google Patents

Abstract

The present invention proposes a graphite coke electrode for an electric furnace, comprising: a graphite coke material and a coal tar pitch, wherein the graphite coke material accounts for 65%-85% of the total weight, the coal tar pitch accounts for 15%-35% of the total weight, and the graphitization degree of the graphite coke material is greater than 70%. The present invention also proposes a preparation process for a graphite coke electrode for an electric furnace, wherein the calcined coke is crushed into a suitable particle size and graphitized to become graphitized coke, the graphitized coke and the crushed graphite material with a graphitization degree greater than 70% are screened and distributed as graphite coke materials, and then the coal tar pitch is added and kneaded according to a proportion, the material is cooled after kneading, the material is evenly heated after the material is cooled, the paste is vibrated and molded, and then the raw product after demoulding is roasted after passing the inspection, and the semi-finished product after roasting is machined, and the electrode of the present invention increases the flexural strength, improves the heat shock resistance index, and greatly reduces the fracture ratio and oxidation consumption before the furnace.

Description

A graphite coke electrode for submerged arc furnace and its preparation process

Technical Field

The invention relates to the technical field of submerged arc furnace electrodes, and in particular to a submerged arc furnace graphite coke electrode and a preparation process thereof.

Background technique

Submerged arc furnace electrodes are essential functional materials for the smelting of industrial silicon, ferroalloys, yellow phosphorus, and calcium carbide by the carbon reduction method of submerged arc furnaces. At present, submerged arc furnaces generally use carbon electrodes. The solid materials required for the preparation of carbon electrodes include graphite blocks, thermal insulation coke (calcined coke, a thermal insulation material used in the graphitization process of lithium battery graphite negative electrode materials), calcined coke, and liquid material coal tar. The process flow is mixing ingredients, kneading paste, cooling paste, equalizing paste temperature, weighing, vibration molding, cooling, roasting and cleaning, mechanical processing, inspection and storage. The volume density of carbon electrodes prepared by this mixing and process is lower than 1.62g/cm³, the flexural strength is less than 7MPa, and the resistivity is higher than 35μQ•m. It is easy to crack and break during use, and the oxidation consumption is high. These phenomena of carbon electrodes affect the normal progress of the submerged arc furnace smelting process to varying degrees.

Summary of the invention

In order to solve the above problems existing in the prior art of the electric arc furnace electrode, the present invention provides an electric arc furnace graphite coke electrode and a preparation process thereof.

The technical solution of the present invention is achieved in this way:

A graphite coke electrode for an ore-fired furnace comprises: a graphite coke material and coal tar pitch, wherein the graphite coke material accounts for 65%-85% of the total weight, and the coal tar pitch accounts for 15%-35% of the total weight; and the graphitization degree of the graphite coke material is greater than 70%.

Preferably, the graphite coke material includes graphite coke material with a particle size less than 24 mm and greater than 4 mm, graphite coke material with a particle size greater than 2 mm and less than 4 mm, graphite coke material with a particle size greater than 1 mm and less than 2 mm, graphite coke material with a particle size greater than 0.075 mm and less than 1 mm, and graphite coke material with a particle size less than 0.075 mm.

A preparation process for a graphite coke electrode for an electric arc furnace as described above comprises the following steps: selecting calcined coke and crushing it into a suitable particle size, graphitizing the crushed calcined coke to become graphitized coke, screening and grading the graphitized coke and crushed graphite material with a graphitization degree greater than 70% as graphite coke materials, batching the ingredients according to the graded particle size of the graphite coke materials, adding coal tar into the ingredients according to a proportion and kneading them, cooling the kneaded paste, kneading the paste at an even temperature after cooling, vibrating the kneaded paste, cooling and demolding the molded product, roasting the demolded raw product after passing the inspection, machining the semi-finished product after roasting, and obtaining a graphite coke electrode for an electric arc furnace after passing the inspection.

Preferably, the suitable particle size for crushing the calcined coke is, according to statistics by weight percentage, that the proportion of calcined coke with a particle size greater than 0.075 mm and less than 4 mm in the total weight is 40%-70%, the proportion of calcined coke with a particle size less than 0.075 mm in the total weight is 20%-35%, and the proportion of calcined coke with a particle size greater than 4 mm and less than 24 mm in the total weight is 10%-25%.

Preferably, the crushed calcined coke is graphitized by subjecting the crushed calcined coke to a high-temperature treatment of 1500°C-3000°C in a graphitization furnace, with a graphitization degree of greater than 70%, to form graphitized coke with a planar hexagonal layered structure.

Preferably, the method of batching according to the graded particle size of the graphite coke material is an intercalation and compaction grading method, specifically: firstly, the graphite coke material with a particle size greater than 4 mm and less than 24 mm is put into a container and fully vibrated to determine the volume base number, and then the graphite coke material with a particle size greater than 2 mm and less than 4 mm is added and stirred and vibrated on the premise of ensuring that the volume base number remains unchanged, and then the graphite coke material with a particle size greater than 1 mm and less than 2 mm is added and stirred and vibrated, and then the graphite coke material with a particle size greater than 0.075 mm and less than 1 mm is added and stirred and vibrated, and finally the graphite coke material with a particle size less than 0.075 mm is added and stirred and vibrated;

The weight percentage of graphite coke materials with different particle sizes in the total weight of graphite coke materials is as follows: the weight of graphite coke materials with a particle size greater than 4mm and less than 24mm accounts for 10%-25%, the weight of graphite coke materials with a particle size greater than 2mm and less than 4mm accounts for 20%-30%, the weight of graphite coke materials with a particle size greater than 1mm and less than 2mm accounts for 5%-15%, the weight of graphite coke materials with a particle size greater than 0.075mm and less than 1mm accounts for 15%-25%, and the weight of graphite coke materials with a particle size less than 0.075mm accounts for 20%-35%.

Preferably, the coal tar pitch is added to the ingredients according to the proportion and kneaded in such a manner that the total weight of the coal tar pitch accounts for 25%-43% of the total weight of all the graphite coke ingredients, and the kneading is performed in a kneading pot through sufficient stirring and kneading to allow the coal tar pitch to fully penetrate into the micropores of the graphitized coke and graphite material and form a pitch film on the surface.

Preferably, the molded product is cooled and demoulded in the following manner: the vibration molded metal mold and the product are cooled simultaneously, and the substantial contraction of the metal mold causes the product inside to be once again shrunk and densified.

Preferably, the unqualified demoulding raw products are crushed into suitable particle sizes for direct batching, and the unqualified calcined semi-finished products are crushed into suitable particle sizes for screening and grading; the ash content of the submerged arc furnace graphite coke electrode after passing the inspection is 0.5%-2.0%, the volume density is 1.62-1.68g/cm³, the flexural strength is 10-16Mpa, the resistivity is 21-27μQ•m, the thermal expansion coefficient is 3.5× ^10-6-3.8 × ^10-6 K, the thermal conductivity is 20-30W/(m•K), and the number of particles with a particle size larger than 0.5mm that can be observed by the naked eye within 200 square centimeters is greater than 1500.

The beneficial effects of the present invention are as follows: the graphite coke electrode of the electric arc furnace of the present invention uses only one solid raw material, namely the graphite coke material, which can ensure that the product will not have problems due to its own performance differences under very harsh working environments, avoid the problems caused by the performance differences when using more than two solid raw materials, and can better adapt to the sudden change from normal temperature to high temperature.

The preparation process of the graphite coke electrode for the electric arc furnace of the present invention is a disruptive process in the carbon industry in that the calcined coke is initially graphitized. The calcined coke is graphitized to transform the amorphous structure into a graphite structure with excellent performance, and then undergoes subsequent preparation processes, so that energy consumption is reduced, and the performance of the finished electrode is greatly improved. The breakage rate is reduced from 2% of the carbon electrode in the prior art to 2‰, and the unit consumption is reduced from 90kg to 50kg, thereby greatly reducing the fracture ratio and oxidation consumption in front of the furnace.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a flow chart of a process for preparing a graphite coke electrode for an electric arc furnace according to Example 2 of the present invention;

FIG. 2 is a flow chart of a process for preparing a graphite coke electrode for an electric arc furnace according to Example 4 of the present invention.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Embodiment 1: A graphite coke electrode for an electric arc furnace, comprising: graphite coke material and coal tar pitch, wherein the graphite coke material accounts for 65%-85% of the total weight, and the coal tar pitch accounts for 15%-35% of the total weight by weight; the graphitization degree of the graphite coke material is greater than 70%. The graphite coke material includes graphite coke material with a particle size greater than 4 mm, graphite coke material with a particle size greater than 2 mm and less than 4 mm, graphite coke material with a particle size greater than 1 mm and less than 2 mm, graphite coke material with a particle size greater than 0.075 mm and less than 1 mm, and graphite coke material with a particle size less than 0.075 mm. The graphite coke material is configured with graphite coke materials of various particle sizes, thereby increasing the flexural strength of the graphite coke electrode for an electric arc furnace.

Graphite coke materials include graphitized coke and other graphite materials with a graphitization degree greater than 70%. Graphite coke materials can be graphite product scraps, furnace electrodes, and graphite waste. Graphite coke materials can be single graphitized coke or graphite scraps or other materials, or a mixture.

The application scenario conditions of the submerged arc furnace electrode are very harsh. The submerged arc furnace electrode is fixed by a holder, and a part of it is located in the high-temperature furnace tower of the submerged arc furnace. After the submerged arc furnace electrode is added with a huge current for conduction, its temperature rises from tens of degrees at a length of only 2 meters to more than two thousand degrees. The temperature gradient is so large that it produces great thermal stress inside it. In addition, the huge current produces a strong magnetic force. The submerged arc furnace electrode works in such an environment and has extremely high requirements for its quality. The submerged arc furnace graphite coke electrode of the present invention uses only one solid material, namely graphite coke material, so as to ensure that the product will not break due to large thermal stress caused by temperature changes due to its own performance differences in a very harsh working environment. Every time the electrode breaks, it is a smelting accident, and the furnace needs to be stopped to salvage the broken electrode. During this period, improper operation may even cause equipment and personal accidents. Reducing the breakage rate is a huge technological advancement.

Embodiment 2: As shown in FIG1 , a process for preparing graphite coke electrode for electric arc furnace is provided. The calcined coke is crushed into suitable particle size, the particle size is less than 24 mm, the crushed calcined coke is subjected to high temperature treatment at 1500°C-3000°C in a graphitization furnace, the degree of graphitization is greater than 70%, and the graphitized coke becomes a planar hexagonal layered structure of graphitized coke, the graphitized coke is batched according to the graded particle size, and then coal tar pitch is added into a kneading pot at a weight of 25% of the total graphite coke batching for kneading, the kneaded paste is cooled, and then kneaded at an even temperature, the kneaded paste is vibrated and formed, the molded product is cooled and demolded, the raw product after demolding is roasted after passing the inspection, the semi-finished product after roasting is machined, and the qualified product is the graphite coke electrode for electric arc furnace.

The preparation process of the present invention prepares ingredients according to the graded particle size, which can enhance the flexural strength. Coal tar is added and kneaded, so that the coal tar is fully infiltrated into the micropores of the graphitized coke to improve the adhesion, so as to facilitate the generation of more adhesive coke during polycondensation during the roasting process, thereby improving the various properties of the product. After the dough is evenly heated, it is more conducive to vibration molding. The purpose of the roasting process is, first, to remove volatile gases, second, to coke the binder, third, to coke and shape the product, fourth, to reduce the resistivity, and fifth, to further shrink the volume, thereby further improving the physical, chemical and mechanical properties of the semi-finished product.

The suitable particle size for crushing calcined coke is statistically analyzed by weight percentage. The proportion of calcined coke with a particle size greater than 0.075mm and less than 4mm is 40%-70% of the total weight, the proportion of calcined coke with a particle size less than 0.075mm is 20%-35% of the total weight, and the proportion of calcined coke with a particle size greater than 4mm and less than 24mm is 10%-25% of the total weight, which is convenient for screening and grading.

The method of batching graphitized coke according to the graded particle size is the embedded dense grading method. First, the graphite coke material with a particle size greater than 4mm and less than 24mm is put into the container and fully vibrated to determine the volume base. On the premise of ensuring that the volume base remains unchanged, the graphite coke material with a particle size greater than 2mm and less than 4mm is then added and stirred and vibrated. Then, the graphite coke material with a particle size greater than 1mm and less than 2mm is added and stirred and vibrated. Then, the graphite coke material with a particle size greater than 0.075mm and less than 1mm is added and stirred and vibrated. Finally, the graphite coke material with a particle size less than 0.075mm is added and stirred and vibrated. ; The weight percentage of graphite coke materials of different particle sizes in the total weight of graphite coke materials is 10%-25% for graphite coke materials with a particle size greater than 4mm and less than 24mm, 20%-30% for graphite coke materials with a particle size greater than 2mm and less than 4mm, 5%-15% for graphite coke materials with a particle size greater than 1mm and less than 2mm, 15%-25% for graphite coke materials with a particle size greater than 0.075mm and less than 1mm, and 20%-35% for graphite coke materials with a particle size less than 0.075mm. This batching method applies the principle of ball stress dispersion, selects larger particles to block the thermal stress generated by the product in the application scenario, and gives play to the irregularity of the graphite coke material, which can make the raw product have higher flexural strength and improve the thermal shock resistance index.

The total weight of coal tar pitch accounts for an arbitrary proportion of the total weight of all graphite coke ingredients between 25% and 43%. The kneading is carried out in a kneading pot through sufficient stirring and kneading to allow the coal tar pitch to fully penetrate into the micropores of the graphitized coke and form an asphalt film on the surface, so that they can adhere well together and improve the adhesion.

The method of cooling and demoulding the molded product is to cool the vibration mold and the product at the same time. The large contraction of the metal mold causes the product inside to be held and shrunk and densified again. The mold is made of metal, and the thermal expansion coefficient of metal is much greater than that of non-metallic materials. With the large contraction of the metal mold, the product inside the mold is held and shrunk and densified again, improving the performance of the product.

The unqualified demoulding raw products are directly batched after being crushed into suitable particle sizes, and the unqualified semi-finished products after being roasted are crushed into suitable particle sizes for screening and grading, and the suitable particle size is consistent with the suitable particle size of the calcined coke; the qualified submerged arc furnace graphite coke electrode has an ash content of 0.5%-2.0%, a volume density of 1.62-1.68g/cm³, a flexural strength of 10-16Mpa, a resistivity of 21-27μQ•m, a thermal expansion coefficient of 3.5× ^10-6-3.8 × ^10-6K , a thermal conductivity of 20-30W/(m•K), and the number of particles larger than 0.5mm can be observed by the naked eye within 200 square centimeters. The electrode obtained in Example 2 has better performance.

The cooling material, dough material and vibration molding in the preparation process of the present invention are the methods in the existing process. The cooling material is to enter the cooling material machine for cooling, the dough material is to exhaust the asphalt fume, and the vibration molding is to put the dough material into the preheated mold of the vibration molding machine at a suitable temperature, and then vibrate, vacuum and hydraulically mold it. The particle size of the crushing in the present invention is consistent with the particle size of the graphite coke material classification.

In Example 2, the calcined coke is crushed before graphitization to enhance the graphitization degree and make its performance more stable. The preparation process of the present invention is a disruptive process in the carbon industry in the initial graphitization. After the calcined coke is graphitized, the amorphous structure is transformed into a planar hexagonal graphite structure, which greatly improves the performance of the finished electrode, and the breakage rate is reduced from 2% of the existing carbon electrode to 2‰, and the unit consumption is reduced from 90kg to 50kg.

Embodiment 3: A process for preparing graphite coke electrodes for electric arc furnaces, comprising: mixing crushed graphite materials with a graphitization degree greater than 70% according to the graded particle size, adding coal tar pitch in an amount of 43% by weight of the total graphite coke ingredients into a kneading pot for kneading, cooling the kneaded paste, kneading the paste at an even temperature, vibrating the kneaded paste, cooling and demolding the molded product, and roasting the raw product after demolding after passing the inspection, machining the semi-finished product after roasting, and obtaining a graphite coke electrode for electric arc furnaces after passing the inspection.

Example 3 is to replace the graphitized coke in Example 2 with a graphite material having a graphitization degree greater than 70%.

The particle size of the graphite material is consistent with the suitable particle size of the calcined coke in Example 2. The way of batching the graphite material according to the graded particles is the same as the way of batching the graded particle size of the graphitized coke in Example 2, and the preparation process is the same. The total weight of coal tar accounts for any value between 25% and 43% of the total weight of all graphite coke ingredients. The kneading is carried out in a kneading pot after sufficient stirring and kneading, so that the coal tar is fully infiltrated into the micropores of the graphite material, and an asphalt film is formed on the surface, so that it can be well adhered together, improving the adhesion. The unqualified demoulding raw products are directly batched after being crushed into suitable particle sizes; the unqualified roasted semi-finished products are crushed into suitable particle sizes for screening and grading.

The performance of the graphite coke electrode for submerged arc furnace prepared in Example 3 is not as good as that of the graphite coke electrode for submerged arc furnace prepared in Example 2, but is better than that of the electrode for submerged arc furnace in the prior art, and meets the inspection qualification standard of the present invention. The inspection qualification standard is the same as that of Example 2.

Graphite materials with a graphitization degree greater than 70% can be graphite blocks or graphite fragments, graphite product scraps, furnace electrodes, and graphite waste materials.

Embodiment 4: As shown in FIG2, a process for preparing graphite coke electrode for electric arc furnace is provided. The calcined coke is crushed into suitable particle size, the particle size is less than 24 mm, the crushed calcined coke is subjected to high temperature treatment at 1500°C-3000°C in a graphitization furnace, the degree of graphitization is greater than 70%, and the graphitized coke becomes a planar hexagonal layered structure. The graphitized coke is mixed with a graphite material having a degree of graphitization greater than 70%, and then the ingredients are proportioned according to the graded particle size. Then, coal tar pitch is added into a kneading pot at a weight of 25% of the total graphite coke ingredients for kneading. The kneaded paste is cooled, and then kneaded at an even temperature. The kneaded paste is vibrated and formed, and the formed product is cooled and demolded. The raw product after demolding is roasted after passing the inspection, and the semi-finished product after roasting is machined to become a graphite coke electrode for electric arc furnace after passing the inspection.

In Example 4, the graphitized coke in Example 2 is replaced by a mixture of a graphite material with a graphitization degree greater than 70% and graphitized coke, and the other preparation processes are the same as those in Example 2. The performance of the graphite coke electrode for the submerged arc furnace prepared in Example 4 is not as good as that of the graphite coke electrode for the submerged arc furnace in Example 2, but is better than that of the graphite coke electrode for the submerged arc furnace in Example 3, and meets the inspection qualification standard of the present invention. The inspection qualification standard is the same as that of Example 2.

The performance of the submerged arc furnace electrode prepared by the conventional process of the prior art was compared with the submerged arc furnace graphite coke electrodes prepared in Example 2, Example 3, and Example 4, respectively. The comparison results are shown in Table 1.

Table 1

According to Table 1, the flexural strength of the graphite coke electrode of the submerged arc furnace prepared by the preparation process of the present invention is greater than 14 MPa, while the flexural strength of the traditional submerged arc furnace electrode is less than 10 MPa, usually 7 MPa. The graphite coke electrode of the submerged arc furnace of the present invention significantly improves the bending strength and the thermal shock resistance index, and greatly reduces the fracture ratio and oxidation consumption in front of the furnace.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A graphite coke electrode for a mineral arc furnace, characterized in that it comprises: a graphite coke material and a coal tar pitch, wherein, by weight percentage, the graphite coke material accounts for 65%-85% of the total weight, and the coal tar pitch accounts for 15%-35% of the total weight; and the graphitization degree of the graphite coke material is greater than 70%. 2. The graphite coke electrode for a submerged arc furnace according to claim 1 is characterized in that the graphite coke material includes graphite coke materials with a particle size less than 24 mm and greater than 4 mm, graphite coke materials with a particle size greater than 2 mm and less than 4 mm, graphite coke materials with a particle size greater than 1 mm and less than 2 mm, graphite coke materials with a particle size greater than 0.075 mm and less than 1 mm, and graphite coke materials with a particle size less than 0.075 mm. 3. A preparation process for the graphite coke electrode of an electric arc furnace as claimed in any one of claims 1-2, characterized in that calcined coke is selected and crushed into a suitable particle size, the crushed calcined coke is graphitized to become graphitized coke, the graphitized coke and the crushed graphite material with a graphitization degree greater than 70% are screened and graded as graphite coke materials, ingredients are prepared according to the graded particle size of the graphite coke materials, coal tar is added to the ingredients according to a proportion and kneaded, the kneaded paste is cooled, the cooled paste is kneaded at an even temperature, the kneaded paste is vibrated and formed, the molded product is cooled and demolded, the demolded raw product is roasted after being inspected and qualified, the semi-finished product after roasting is machined, and after passing the inspection, it becomes a graphite coke electrode for an electric arc furnace. 4. The preparation process according to claim 3 is characterized in that the suitable particle size of the calcined coke after crushing is, according to statistics by weight percentage, the proportion of calcined coke with a particle size greater than 0.075 mm and less than 4 mm in the total weight is 40%-70%, the proportion of calcined coke with a particle size less than 0.075 mm in the total weight is 20%-35%, and the proportion of calcined coke with a particle size greater than 4 mm and less than 24 mm in the total weight is 10%-25%. 5. The preparation process according to claim 3 is characterized in that the crushed calcined coke is graphitized by subjecting the crushed calcined coke to a high-temperature treatment of 1500° C. to 3000° C. in a graphitization furnace, wherein the degree of graphitization is greater than 70%, thereby obtaining graphitized coke with a planar hexagonal layered structure. 6. The preparation process according to claim 3 is characterized in that the method of batching according to the graded particle size of the graphite coke material is an intercalation and compaction grading method, specifically: firstly, the graphite coke material with a particle size greater than 4 mm and less than 24 mm is loaded into a container and fully vibrated to determine the volume base number, and then the graphite coke material with a particle size greater than 2 mm and less than 4 mm is added and stirred and vibrated on the premise of ensuring that the volume base number remains unchanged, and then the graphite coke material with a particle size greater than 1 mm and less than 2 mm is added and stirred and vibrated, and then the graphite coke material with a particle size greater than 0.075 mm and less than 1 mm is added and stirred and vibrated, and finally the graphite coke material with a particle size less than 0.075 mm is added and stirred and vibrated; The weight percentage of graphite coke materials with different particle sizes in the total weight of graphite coke materials is as follows: the weight of graphite coke materials with a particle size greater than 4mm and less than 24mm accounts for 10%-25%, the weight of graphite coke materials with a particle size greater than 2mm and less than 4mm accounts for 20%-30%, the weight of graphite coke materials with a particle size greater than 1mm and less than 2mm accounts for 5%-15%, the weight of graphite coke materials with a particle size greater than 0.075mm and less than 1mm accounts for 15%-25%, and the weight of graphite coke materials with a particle size less than 0.075mm accounts for 20%-35%. 7. The preparation process according to claim 3 is characterized in that the coal tar pitch is added to the ingredients according to a proportion and kneaded in such a manner that the total weight of the coal tar pitch accounts for 25%-43% of the total weight of all the graphite coke ingredients, and the kneading is carried out in a kneading pot through sufficient stirring and kneading to allow the coal tar pitch to fully infiltrate the micropores of the graphitized coke and graphite material and form a pitch film on the surface. 8. The preparation process according to claim 3 is characterized in that the method of cooling and demolding the molded product is: the vibration-molded metal mold and the product are cooled simultaneously, and the substantial contraction of the metal mold causes the product inside to be once again shrunk and densified. 9. The preparation process according to claim 3 is characterized in that the unqualified demoulding raw products are directly batched after being crushed into suitable particle sizes, and the unqualified roasted semi-finished products are crushed into suitable particle sizes for screening and grading; the ash content of the submerged arc furnace graphite coke electrode after passing the inspection is 0.5%-2.0%, the volume density is 1.62-1.68g/cm³, the flexural strength is 10-16Mpa, the resistivity is 21-27μQ•m, the thermal expansion coefficient is 3.5× ^10-6-3.8 × ^10-6K , the thermal conductivity is 20-30W/(m•K), and the number of particles with a particle size greater than 0.5mm that can be observed by the naked eye within 200 square centimeters is greater than 1500.