How are graphite electrodes used for EAF steelmaking?

The process of electric arc furnace steelmaking is complex and highly technical, but the basics are easy to understand. Graphite electrodes used in eaf, which generate heat to melt iron ore and other materials and extract pure iron from them to make steel. Electric arc furnaces work similarly to traditional blast furnaces, except they use electricity rather than coal or natural gas as their energy source. In this article, we’ll explore graphite electrodes used in electric arc furnaces, who uses them and why, how much current passes through a typical EAF electrode, and how long they last before needing replacement.

How are graphite electrodes used for EAF steelmaking steel production?

Graphite electrodes are used in electric arc furnace (eaf) as a carbon source and conductor for steelmaking. Electric arc furnaces refine iron and produce steel, providing the heat necessary to melt iron ore, remove impurities from the molten iron product, and create slag that separates from purer metal.

Melting the Raw Materials:

Electric Arc Furnaces utilize graphite electrodes to generate intense heat through an electric arc. The electrodes are inserted vertically into the EAF, and when an electric current passes through them, it creates a high-temperature arc between the electrodes and the metallic charge inside the furnace. This arc rapidly heats and melts the raw materials, including scrap steel and other metal components, transforming them into a molten state.

Facilitating the Steel Refining Process:

Once the raw materials are melted, graphite electrodes continue to play a crucial role in the refining stage of eaf steelmaking. During this process, various operations are performed to adjust the chemical composition, remove impurities, and control temperature. They provide the necessary heat and electrical conductivity to carry out these refining processes effectively.

Continuous Casting:

In the final stage of steelmaking, where the molten steel is cast into various shapes, graphite electrodes are utilized in continuous casting processes.

They help maintain the temperature of the molten steel and prevent premature solidification during the casting process. Electrical current is also provided to promote solidification and form a solid steel product.

What are the types of graphite electrodes used for eaf steelmaking?

The most commonly used types in EAF include: UHP、HP and RP. Graphite electrodes are made from petroleum coke and pitch coke, mixed with a binder, and pressed into a mold. The production of HP and UHP grades uses needle coke as the raw material. The production process uses multiple impregnation and roasting to increase the graphitization temperature and improve the binder and impregnant accordingly. Generally, according to the tonnage of the electric arc furnace, the electrodes of the specifications are selected for use.

How much current passed through ?

The amount of current that passes through a typical graphite electrode is usually in the range of 10-20 A. For example, a large electrode might have a current density of over 100 A/cm2.  Because it has low resistivity and is a good conductor.

What type of steel does an Electric Arc Furnace (EAF) produce?

Steel is made by extracting the iron and adding carbon when iron ore and coke are heated to a temperature of 2,700°F (1,500°C) in an electric arc furnace (EAF).

The types of steel produced include carbon steel, alloy steel, cast steel, pure iron and alloys, etc.

Conclusion

Graphite electrodes have high electrical conductivity, heat resistance and mechanical strength. So it is ideally suited for eaf steelmaking, refining and casting processes. It has become an indispensable conductor electrode for modern electric arc furnace steelmaking.