The advantages of dc arc melting furnaces over ac furnaces in the production of high-quality refractories and conducting and insulating materials are discussed.Currently, the Arcterm and Comterm research and production firms are developers and suppliers of dc and ac arc melting furnaces; when in service, the use of these facilities provides a high rate of profit and a short payback time.Studies that were carried out for many years at VNIIÉTO (All-Union Research Institute for Electrothermal Equipment, Moscow, Russia) jointly with leading organizations in Russia in the field of ferrous and nonferrous metallurgies, production of refractories, and other sectors of industry, and the expertise gained in the use of various metal treatment equipment have led to the conclusion that dc arc furnaces can be effectively used in a whole range of technological applications.Dc arc furnaces provide economies in energy, materials, and environmental costs; their use improves labor conditions and provides routes towards reprocessing of slag wastes and extracting valuable metals from them. The dc arc furnacebased technologies allow production of high-quality metals and alloys, reduction of the operating cycle, and expansion in the product range.Dc arc furnaces are used to make low-carbon and stainless (in particular, tungsten-containing) steels, gray iron, high-strength vanadium cast iron; aluminum and aluminumbased alloys; copper and copper-based alloys; silver, cobalt, nickel, manganese, and ferroalloys. Using the dc arc furnace technology, depletion melting of the slag of nonferrous and noble metals, refining and other processes, such as ore-reducing melting of calcium silicate and calcium carbide, reduction of silicon (for solar power engineering and semiconductor industry), organosilicon synthesis, manufacture of electrofused corundum, electrode product graphitization, waste processing and extraction of valuables components, production of phosphorus, silicon carbide, and electrode mix can be carried out.In the wide range of technological processes that are realized using dc furnaces, in this paper we consider in some detail those concerned with the steel-making in dc arc furnaces, with a 30-year-long history in industrial service.
AC ARC FURNACES (AAF) AS AN ALTERNATIVE TO DC ARC FURNACES (DAF)A promising trend in electric steel production -viewed from the standpoint of an energy and materials-efficient economy and marginal environmental impact -is the use of dc steel-melting furnaces or retrofitting of the existing ac arc furnaces to enable their powering with direct current.At present, the DAF design has made use of the best that was achieved in the years-long history of the AAF development, in particular, refractory materials for the lining, systems of charging materials to the furnace, metal processing technologies, etc. DAF can operate with a complete discharge of molten metal ("unbogged," in a specialists jargon), or with a partial discharge ("bogged down"). In steel-making, DAF can operate in an oxygen-blown regime. This ...
