An electric arc furnace, also known as an electric arc furnace, an installation with an electric arc materials, typically metals or heat melting point. A typical electric arc furnace melts the material, or "charge" as is known, by an electric current through the load by means of a set of electrodes. A combination of the heat generated by the current passage and the sparks melts the surface of the charge material. EAFS found in research laboratories and dentures, cast iron foundries and steel production facilities and can internal capacities ranging from a few pounds to have 400 tons or more. Ovens have several distinct advantages over other types of furnace.
An electric arc furnace generally consists of a shell with side walls and a dished bowl at the bottom. A sliding roof section, which makes lowered the graphite electrodes, encompasses the furnace. The bowl portion of the reservoir is lined with a layer of refractory material known as the hearth. The crane or nozzle used for the discharge of molten metal either on the side of the reservoir, or placed at the bottom of the bowl. The electrodes are generally circular in cross-section and made of threaded sections that make it possible to be added as new sections of the electrode burns.
Either AC or DC power sources are used in an electric arc furnace. The average steel mill arc furnace operates at a 400-900 volt power supply at 44,000 amperes or more transformers come with ratings of around 60 million volt-amperes. A furnace of this type may be about 80 tons of molten steel per hour. Arc furnaces vary in size from small units to keep used in research laboratories around a pound of loading to huge steel mill installations capable of melting hundreds of tons of material. The largest of these furnaces have a capacity of over 300 tons, and use power of 300 MVA or more.
The process of arc melting is quite simple. As soon as the bowl or hearth of the furnace is filled with a feed material, the electrodes are lowered until they contact the cargo. The electric current is then applied, usually start at lower voltages to the process. The current through the load, together with the radiation energy from the arcing increases the heat load of up to a point where it melts. Once the charge is completely melted, the temperature and chemical composition is controlled by remote probes or applicators; if everything is correct, the molten metal can be tapped or drained.
The raw materials used in the furnaces are often complemented by the addition of pig iron, burnt lime and dolomite. These additives promote the proper chemical balance in the molten steel and slag forming surface floating impurities and isolates the cargo. Arc Furnace systems offer much more flexibility than other types of oven; they are able to use an exclusive supply of scrap material, and their output can be varied to suit the demand. Ovens may be closed quickly and restart which is not the case with blast furnaces. They are also cheaper to install and use less power to operate per ton of finished product.