Industrial electric heating furnaces – Arc furnace device – Charging or discharging
Reexamination Certificate
2000-12-18
2002-05-14
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Arc furnace device
Charging or discharging
C373S081000
Reexamination Certificate
active
06389054
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scrap charging apparatus for an electric furnace used in a steel making process and more particularly, to such an apparatus embodying a construction and an arrangement of component parts to minimize the requirement of floor space in a steel making and passage of the scrap into a furnace in an incremental fashion to maintain flat bath operation by the furnace.
2. Description of the Prior Art
The charging of scrap into an electric furnace, particularly in an electric arc furnace, may be carried out by the use of sequential use of conveyors delivering the scrap from a remote storage area to the furnace. The scrap is allowed to fall through the top of the furnace after removal of the furnace roof and electrodes from the furnace interior. Many tons of scrap will be charged and impact with the refractory lining of the furnace cannot be avoided requiring repair to the damage refractory. The conveyors require a continuous presence along a usually extensive course of travel by the scrap. Conveyors must be of a heavy duty construction to rapidly transport the scrap need for a service charge and also to withstand the intense heat flowing from the top of the furnace. The use of a large liquid metal heel at the end of tapping of the furnace to promote flat bath furnace operation would be undesirable because splashing of the liquid metal as the scrap impacts with the liquid metal. Well drastically shortening the life of the furnace side walls, therefor it is usual to reestablish a liquid metal bath by melting scrap by using heat provided by the operation of the electrodes. As the scrap melts about the electrodes, cold spots form outwardly from the electrodes from which eventually cave in and instances fall against the electrodes causing electrode damage.
Accordingly, it is an object of the present invention to provide a scrap charge for an electric steel making furnace to charge scrap in a generally horizontal direction form a bunker to the furnace.
It is another object of the present invention to provide a skip hoist system to load a scrap charging bunker for reducing the requirement of floor space about an electric steel making furnace.
It is a further object of the present invention to provide a scrap storage bunker including diverging end wall communicating with an underlying scrap charging chutes having walls that enlarge the cross sectional are in the chute in the direction to an electric steel making furnace to maintain un impeded flow of scrap by the even increasing size of the scrap conducting space.
It is a further object of the present invention to provide a generally horizontal scrap charging chute communicating with a retractable fluid cold chute extending into the interior of an electric steel making furnace to establish a scrap fall space with a bath of liquid steel remaining the furnace after tapping.
BRIEF SUMMARY OF THE INVENTION
According to the present invention there is provided a scrap charging apparatus for an electric arc furnace, the apparatus including the combination of a scrap holding bunker having diverging end walls extending between converging side walls, the scrap burden along boundaries formed by the diverging end walls providing an impetus in the bunker for scrap flow to an underlying scrap delivery chute, the scrap delivery chute defining an elongated scrap carrying trough having a greater width than the exit width of the scrap holding bunker for delivering scrap to a charging opining for an electric arc furnace, a superstructure supporting the scrap holding bunker at an elevated and lateral spaced location from an electric arc furnace, a ram controlled by a drive to incrementally advance scrap along the scrap delivery chute for introducing successive preselected volumes of scrap to a charging opining for an electric arc furnace, and a conveyor for supplying scrap to the scrap holding bunker.
REFERENCES:
patent: 1338881 (1920-05-01), Stock
patent: 1422135 (1922-07-01), Rogatz
patent: 3462538 (1969-08-01), Pellegrini et al.
patent: 3622141 (1971-11-01), Brusa
patent: 4023784 (1977-05-01), Wallace
patent: 4225745 (1980-09-01), Harwell
Hoang Tu Ba
Poff Clifford A.
SMS Demag Inc.
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