Analysis of the production process of self-baking electrode paste
Self-baking electrode paste is an indispensable and important material in electric furnace smelting, especially in ferroalloy electric furnaces, calcium carbide furnaces and other high-temperature smelting processes play a key role.This article will analyze in detail the production process of self-baking electrode paste, from raw material selection, mixing and stirring, molding and drying to final use, and comprehensively elaborate on its production process and technical points.
1. Selection and preparation of raw materials
The raw materials of self-baking electrode paste mainly include anthracite, coke, asphalt and tar.The choice of these raw materials is directly related to the performance and quality of the electrode paste.
Anthracite coal: It needs to be calcined at a high temperature above 1200℃ to remove volatile components. The ash content is less than 8%, the volatile components are less than 5%, the sulfur content is low, the specific resistance is greater than 1000_uΩ·m, and the thermal strength index is greater than 60%.
Coke: As an aggregate, its ash content must be less than 14%.
Asphalt and tar: As a binder, the softening point of asphalt is required to be 60~75℃, the ash content is less than 0.3%, the moisture content is not greater than 0.5%, the volatiles are 60%~65%, and the free carbon content is not greater than 20%~28%; the tar density is controlled at 1.16~1.20g/cm3, the moisture is not greater than 2.0%, the ash content is not greater than 0.2%, and the free carbon content is not greater than 9%.
2. Mixing and stirring
After the raw materials are ready, enter the mixing and stirring stage.The purpose of this step is to fully mix the various raw materials evenly to form an electrode paste with a certain viscosity and fluidity.
Crushing and screening: Anthracite coal and coke need to be broken and screened first to control the particle size distribution and improve the compactness and conductivity of the mixture.Generally, it is required that anthracite coal be broken to less than 20mm, and coke be ground into powder and added.
Batching and kneading: The crushed and sieved raw materials are batched in a certain proportion, coal asphalt is added, and kneading is carried out in a kneading machine.The kneading temperature needs to be more than 70℃ higher than the softening point of the binder, and the stirring time is not less than 30 minutes to ensure that the raw materials are fully mixed evenly.
3. Forming and drying
The evenly mixed electrode paste is made into a specific shape of electrode paste through molding equipment, and then dried.
Molding: Electrode paste molding generally adopts extrusion molding or pouring molding methods to make electrode paste columns suitable for electrode shells.
Drying: The electrode paste after forming needs to be dried to remove excess moisture and volatiles and improve the strength and conductivity of the electrode.The drying temperature and time need to be adjusted according to the specific process requirements, and generally need to be dried at high temperature for several hours to dozens of hours.
4. The self-baking process
The baking process of self-baking electrode paste is carried out in an electric furnace. As the electric furnace heats up, the electrode paste gradually softens, melts and sinters, and is finally converted into a conductive electrode.
Roasting: The electrode paste is subjected to high temperature in an electric furnace, gradually softening and melting.At this time, the volatiles in the electrode paste continue to be discharged, and the organic matter in the binder reacts with pyrolysis and carbonization to form a solid electrode structure.
Sintering: As the temperature rises further, the electrode paste is gradually sintered to form an electrode with a certain strength and conductivity.In the sintering process, the electrode shell also plays an important conductive and supporting role.
5. Use and maintenance
The self-baking electrode needs to be lengthened and consumed regularly during use to maintain the working length and performance of the electrode.
Connection length: As the production progresses, the lower electrode is gradually consumed, and the electrode paste needs to be added to the electrode shell regularly to supplement the electrode length.During the addition process, attention should be paid to controlling the height of the paste column and the verticality of the electrode to ensure the sintering quality of the electrode.
Consumption: The electrode is continuously vaporized and ionized at the high temperature of the arc to maintain the stable combustion of the arc.The consumption rate of the electrode is affected by a variety of factors, including the fixed carbon content of the electrode, porosity, charge-to-coke ratio, electrode current density, etc.
6. Summary
The production process of self-baking electrode paste involves multiple links such as raw material selection, mixing and stirring, forming and drying, and self-baking.Through strict process control and quality control measures, electrode paste products with excellent performance and stable quality can be produced.In the smelting process of electric furnaces, self-baking electrode paste, as an important conductive material, is of great significance to ensure the stable operation and efficient production of electric furnaces.
