How an Electric Arc Furnace Works Steel Foundations
Unlike the blast furnace that burns coal and natural gas for fuel, an electric arc furnace (EAF), uses electrical energy to heat and melt the raw materials for iron and steel.
To start the electric arc furnace process, recycled steel scrap or other iron-rich raw materials are charged into the furnace along with slag forming materials. Next, three large graphite electrodes send high-powered electric arcs through the scrap generating temperatures up to 3,000° F. At this temperature, the iron-rich, raw materials melt into liquid steel and a protective slag layer is formed.
Many EAFs also utilize gas burners in the walls of the furnace to inject oxygen, carbon, and/or natural gas. The utilization of gas burners improves heat utilization and slag development. Once the steel has been completely melted, it is tapped into a ladle for further processing and the excess slag is poured off in preparation for the next heat.
The main task of most modern electric arc furnaces is to convert solid, iron-rich raw materials, such as steel scrap, direct reduced iron (DRI), and/or hot briquetted iron (HBI) to liquid crude steel as fast as possible. The liquid crude steel is then refined further in subsequent secondary steelmaking processes.
When compared to blast furnaces, EAFs are very popular when installing new steelmaking facilities for several reasons:
- They are much smaller and cheaper to build.
- Their small size allows them to be built near the point of use.
- They are highly efficient and automated.
- They have much less environmental impact.