DC ARC MELTING FURNACES
S. M. Nekhamin,
A. G. Lunin,
M. M. Krutyanskii,
and A. K. Filippov
Translated from Novye Ogneupory, No. 11, pp. 13 – 15, November, 2004.
Original article submitted April 15, 2004.
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 pro
duction 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, produc-
tion of refractories, and other sectors of industry, and the ex-
pertise gained in the use of various metal treatment equip-
ment have led to the conclusion that dc arc furnaces can be
effectively used in a whole range of technological applica-
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 furnace-
based 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 stain
less (in particular, tungsten-containing) steels, gray iron,
high-strength vanadium cast iron; aluminum and aluminum-
based 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-re
ducing melting of calcium silicate and calcium carbide, re
duction of silicon (for solar power engineering and semicon
ductor 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 re
alized using dc furnaces, in this paper we consider in some
detail those concerned with the steel-making in dc arc fur-
naces, 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 develop
ment, in particular, refractory materials for the lining, sys
tems of charging materials to the furnace, metal processing
technologies, etc. DAF can operate with a complete dis
charge of molten metal (“unbogged,” in a specialists jargon),
or with a partial discharge (“bogged down”). In steel-mak
ing, DAF can operate in an oxygen-blown regime. This
makes it possible to increase the DAF output and to reduce
the power consumption to 50 – 80 kW × h/ton.
The dc arc discharge requires the use of regimes for heat
ing and melting metals that are somewhat different from
those used in AAF technologies. The difference is mainly as
sociated with the following features: (i) absence of periodic
changes in the arc discharge polarity; here the roof the graph
ite electrode serves as cathode, rather than the electrode and
the metal operating in alternation: (ii) a single roof electrode
(rather than three electrodes) is used; (iii) the working cur
rent flows over the bath volume from the anode electrode
Refractories and Industrial Ceramics Vol. 46, No. 1, 2005
1083-4877/05/4601-0037 © 2005 Springer Science+Business Media, Inc.
Arcterm Research and Production Co.; Comterm Research and
Development Co. Moscow, Russia.