Arc furnace

Although rocking of the furnace to intermittendy cover and hence protect up to 90% of the refractory, as well as improved refractories, has done much to make the indirect-arc furnace more viable, these furnaces are becoming less common, primarily due to high operating costs as a result of erosion of the refractory by the intense arc radiation. 

Open-Arc Furnaces. Most of the open-arc furnaces are used in melting and refining operations for steel and iron (Fig. 1). Although most furnaces have three electrodes and operate utilizing three-phase a-c power to be compatible with power transmission systems, d-c furnaces are becoming more common. Open-arc furnaces are also used in melting operations for nonferrous metals (particulady copper), slag, refractories, and other less volatile materials. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

The roof, in the form of a dome, is either comprised of refractory brick held in place by a water-cooled steel roof ring, or it may be composed of water-cooled panels. Sometimes water-cooled rings or glands are placed on the roof around the electrodes to maintain the refractory. On high power furnaces refractory is used around the electrodes to minimize the possibility of electrical short circuits. 

Refractory Linings. The refractory linings (2,3) for the hearth and lower walls of furnaces designed for melting ferrous materials may be acidic, basic, or neutral (see Refractories). Silica has been widely used in the past, and is still being used in a number of iron and steel foundries. Alumina, a neutral refractory, is normally used for furnace roofs and in the walls for iron foundries, but basic brick can also be used in roofs (4). 

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Aluminium nitride can also be prepared by heating a mixture of aluminium oxide and carbon in nitrogen in an electric arc furnace ... 

If an excess of magnesium is used, magnesium silicide, Mg2Si, is also produced.) The silicon obtained is a light brown hygroscopic powder. Crystalline or metallic silicon is obtained industrially by the reduction of silica with carbon in an electric arc furnace ... 

Arc furnaces Archery bows Archimedes number Architectural fabrics Architectural lamnates Arc-jet thrusters... 

FURNACES,ELECTRIC - ARC FURNACES] (Vol 12) egulatory agencies piEGULATORY AGENCIES - POWER GENERATION] (Vol 21) [FURNACES,ELECTRIC - RESISTANCEFURNACES] (Vol 12)... 

Open-arc furnaces Open-celled foam Open-circuit potential Open-mold processes Open-pit mining Operating line... 

Plasma arc cutting Plasma-arc devices Plasma-arc furnace Plasma arc spray Plasma arc welding... 

Tetrafluoroethylene was first synthesized in 1933 from tetrafluoromethane, CF, in an electric arc furnace (11). Since then, a number of routes have been developed (12—18). Depolymerization of PTFE by heating at ca 600°C is probably the preferred method for obtaining small amounts of 97% pure monomer on a laboratory scale (19,20). Depolymerization products contain highly toxic perfluoroisobutylene and should be handled with care. 

Fig. 1. Main types of electric furnaces (a) resistance furnace, indirect heat (resistor furnace) (b) resistance furnace, direct heat (c) arc furnace (d) induction furnace. A, charge to be heated or melted B, refractory furnace lining C, electric power supply D, resistors E, electrodes F, electric arc G,...

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