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What’s called “Electric Arc Furnace(EAF) in the tool steel industry ? An electric arc furnace (EAF) is a furnace that heats charged material by means of an electric arc. Industrial arc furnaces range in size from small units of approximately one ton capacity (used in foundries for producing cast iron products) up to about 400 ton units used for secondary steelmaking. Arc furnaces used in research laboratories and by dentists may have a capacity of only a few dozen grams. Industrial electric arc furnace temperatures can be up to 1,800 °C (3,272 °F), while laboratory units can exceed 3,000 °C (5,432 °F). Arc furnaces differ from induction furnaces in that the charge material is directly exposed to an electric arc, and the current in the furnace terminals passes through the charged material. 1. Construction An electric arc furnace used for steelmaking consists of a refractory-lined vessel, usually water-cooled in larger sizes, covered with a retractable roof, and through which one or more graphite electrodes enter the furnace. The furnace is primarily split into three sections: 1. the shell, which consists of the sidewalls and lower steel "bowl" 2. the hearth, which consists of the refractory that lines the lower bowl 3. the roof, which may be refractory-lined or water-cooled, and can be shaped as a section of a sphere, or as a frustum (conical section). The roof also supports the refractory delta in its centre, through which one or more graphite electrodes enter 3. the hearth may be hemispherical in shape, or in an eccentric bottom tapping furnace (see below), the hearth has the shape of a halved egg. In modern meltshops, the furnace is often raised off the ground floor, so that ladles and slag pots can easily be manufactured under either end of the furnace. Separate from the furnace structure is the electrode support and electrical system, and the tilting platform on which the furnace rests. Two configurations are possible: the electrode supports and the roof tilt with the furnace, or are fixed to the raised platform. 2. Advantages of electric arc furnace for steelmaking The use of EAF allows steel to be made from a 100% scrap metal feedstock. This greatly

reduces the energy required to make steel when compared with primary steelmaking from ores. Another benefit is flexibility: while blast furnaces cannot vary their production by much and can remain in operation for years at a time, EAF can be rapidly started and stopped, allowing the steel mill to vary production according to demand. Although steelmaking arc furnaces generally use scrap steel as their primary feedstock, if hot metal from a blast furnace or direct-reduced iron is available economically, these can also be used as furnace feed. As EAFs require large quantities of electrical power, many companies schedule their operations to take advantage of off peak electricity pricing. Editor : Mr. Jie Yun Lee (Engineer) Tel: +86 714 3064045, E-mail : [email protected] Company : Alta Special Steel Co.,Ltd Declaration : Alta Special Steel Co.,Ltd enjoy the ownership to this article, reproduced, please indicate the source!