Electric arc furnaces produce steel directly from scrap. This can be supplemented by other inputs like direct reduced iron and pig iron. They account for about one third of global steel output. Basic oxygen furnace (converter) steelmaking accounts for the rest.
The EAF is a refractory-lined vessel with a retractable cover through which large graphite electrodes are lowered once the scrap has been charged and the furnace top closed. EAFs are usually of 60-150t capacity per melt, but occasionally larger. However, they are usually much smaller than BOFs.
Melting occurs due to the energy released by arcing between electrode and scrap. There are normally three electrodes, but only one with direct current furnaces. Much effort has been directed at minimizing the time from scrap charging to steel pouring (tap-to-tap time). It is now standard practice to transfer steel to a separate furnace for alloying modifications (secondary metallurgy) to free-up the EAF for the next charge. Scrap pre-heating and oxygen injection also raise productivity and reduce energy use. And for more detail click and see wikipedia entry.