Industrial electric heating furnaces – Arc furnace device – Furnace body detail
Patent
1996-12-05
1998-09-15
Hoang, Tu B.
Industrial electric heating furnaces
Arc furnace device
Furnace body detail
373108, F27D 100
Patent
active
058090550
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metallurgical vessel heated by direct current, in particular for the production of ferroalloys, including a metallic jacket lined with refractory material and a botton electrode.
2. Description of the Related Art
Vessels operated by means of direct current, such as furnaces, ladles or the like have, in addition to the electrode which projects in the form of a rod into the vessel and is generally designed as a cathode, an anode arranged in the bottom or in the region of the bottom. This contact device serves the aim of establishing a cathodic contact at the periphery of a molten metal bath in a metallurgical vessel. Metal rods passed through the bottom of the vessel or electrically conducting refractory rammed mixes or bricks are used as anodes. German patent publication DE 31 07 454 A1 discloses an electrode contact device arranged in the form of a ring or part of a ring on a common circle along the periphery of the ladle. This contact device is connected to conducting inserts, which can also occupy a relatively small portion of the bottom of the vessel.
In the case of the bottom electrode known from this publication, only part of the bottom of the vessel is designed as an electrode. Moreover, the known electrode is suitable only for relatively small vessels since no compensation is provided for the thermal expansion of the bottom, particularly in the case of relatively large vessels.
A bottom for an electrically heated melting furnace, in particular a direct current electric-arc furnace, is disclosed in German patent publication DE 35 34 750 C2. In this publication, at least the central area of an electrically heated melting furnace is provided with layers of electrically conducting material that serve as electrodes and a nonmetallic material with a high melting point is used. This publication gives no indication of how the contact between the power supply lead and the electrically conducting bottom is to be made.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a bottom electrode of a metallurgical vessel which is heated by direct current and forms an electrical contact over as large an area as possible. At the same time, reliable current transfer between the melt and the electrode device in the bottom of the vessel is ensured in the case of a power supply lead which is independent of the thermal load on the refractory lining.
According to the present invention, the bottom of the metallurgical vessel, which is arranged below the refractory side wall, is constructed from electrically conducting material. Metallic plates are provided at the periphery of the bottom, and each of the plates is connected to current contacts that project from the furnace vessel. Placed next to one another, the individual plates form a contact-plate ring which is arranged parallel to the center line and which rests snugly against the outer edge of the electrically conducting bottom and is thus capable of transmitting the electric current reliably. Rod-like elements, which radiate outwards through the vessel wall and are connected to a bus line, are arranged on the plates and connected closely to them. Reliable contact with the plates, which are preferably produced from copper and have an L-shaped profile with a limb directed away from the center of the vessel, is achieved by virtue of the thermal expansion of the refractory material. The contact plates within the bottom lining are protected from corrosion by the exclusion of air.
A high effectiveness of the contact between the molten metal bath and the copper plates is achieved by the use, in the bottom, of the refractory material that conducts electric current. By arranging the entire electrode below the precipitate of the bath, contact which is very largely independent of the level of filling is achieved. Given the very different electrical conductivity of the very wide range of different metals to be produced this has a clearly positive effect in terms of proc
REFERENCES:
patent: 1299110 (1919-04-01), Booth
patent: 1806210 (1931-05-01), Miguet
patent: 4692930 (1987-09-01), Radke et al.
patent: 4853941 (1989-08-01), Rappinger et al.
patent: 5255284 (1993-10-01), Meredith
Konig Heribert
Stark Heinz
Hoang Tu B.
Mannesmann Aktiengesellschaft
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