Long History of Electric Arc Furnace Steel Making
Electric Arc Furnaces (EAF) have been used since the 19th century to melt iron. Different attempts were made but the first successful electric arc furnace was developed and patented by James Burgess Readman in 1888. The furnace was specifically crafted for the production of phosphorus.
EAFs also played a pivotal role during World War 2, used primarily of the production of different steel alloys. After the war, the adoption of a mini mill concept integrated with EAFs had helped many European war ravaged countries to start production of electric steel.
Melting Metal with Graphite Electrodes
EAFs are basically a huge electrical circuit that produces heat to melt metal. The construction consists of heat and corrosive resistant vessel with a lid that has three graphite electrodes.
The vessel is “charged” with scrap, light metal pieces sandwiching heavy pieces. The electrodes are lowered and when they touch the metal, low electric voltage is passed. The arc is struck and the graphite electrodes press down, going into the scrap and the electrical energy creating enormous amounts of heat to melt the scrap metal.
As the electrodes bore further into the metal, the electrical voltage is increased since the arcs formed will not be able to touch the sides of the vessel and damaging it. The electrodes are then raised back slightly, allowing a space in which the molten metal can pool up easily.
Advantages of Electric Arc Furnace Steelmaking
Once the impurities that float on the top are removed, the vessel is tilted to pour out the purified liquid metal into pre heated ladles to be cooled off.
EAFs offer advantages over other methods as steel can be made from 100% scrap. The overall energy requirements from making steel from ores is minimal. Another advantage is that unlike ore production of steel, EAFs can be rapidly started or shut down, allowing for batch operations. There is not much wear and tear involved, with usually the graphite electrodes being worn away. The electrodes are manufactured in a modular way where more pieces of electrodes are added as the old ones erode.
Sources for Electric Arc Furnace Steelmaking
United States Patent and Trademark office: %252Fnetahtml%252FPTO%252Fpatimg.htm
Modeling and Control of an Electric Arc Furnace, Benoit Boulet, Gino Lalli and Mark Ajersch, Centre for Intelligent Machines, McGill University, 3480 University Street, Montréal, Québec, Canada H3A 2A