Specialized metallurgical processes – compositions for use therei – Processes – Electrothermic processes
Reexamination Certificate
1997-09-12
2001-05-08
King, Roy (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Electrothermic processes
C075S961000, C075S010620, C075S561000, C075S570000
Reexamination Certificate
active
06228137
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a foaming slag above stainless steel melted in an electric furnace.
2. Discussion of the Background
In the field of melting stainless steel in an electric furnace, the furnace burden of iron scrap, offcuts and ferroalloys is converted into liquid metal by virtue of the generation of electric arcs between the furnace electrodes and said burden.
The production of the steel gives rise to residual products such as dust which is recovered by dust precipitators, approximately 90% of which is recycled in the form of pellets reintroduced into the electric furnace. The remaining 10%, containing too much zinc oxide, is at present stored. The slag is removed after melting.
In the field of melting of nonstainless steels, the principle of foaming slag is based on the reduction of the iron oxide present in the slag. The reduction of the iron oxide is performed by injecting carbon powder into the furnace; a reduction which gives rise to carbon monoxide. The bubbles of carbon monoxide trapped in the molten slag make the latter foam and consequently increase its volume. The slag in foam form coats the end of the electrode and protects the refractories from the electric radiation, and this allows a saving, in the consumption of the electrode, in electricity consumption and in the consumption of the refractories.
In the case of the melting of stainless steels the slag is not sufficiently rich in iron oxide and, as a result, the principle of the foaming slag employed in the production of nonstainless steels is no longer applicable.
SUMMARY OF THE INVENTION
One object of the invention is to provide a process for generating a controlled and stable foaming slag above a molten stainless steel, in an electric furnace, by modifying the slag so as to create foaming in said slag.
REFERENCES:
patent: 4528035 (1985-07-01), Simpson, Jr. et al.
patent: 4913732 (1990-04-01), Miyano et al.
patent: 4986847 (1991-01-01), Knapp et al.
patent: 5493580 (1996-02-01), Fudala et al.
patent: 5733356 (1998-03-01), Konig et al.
patent: 0 162 679 (1985-11-01), None
patent: 0 655 508 (1995-05-01), None
patent: 88 577 (1995-06-01), None
Database WPI, Section Ch, Week 7808, Derwent Publications Ltd., London, GB; and JP 53 001 618 A, (Nisshin Steel Co. Ltd.), Jan. 9, 1978.
Bletton Olivier
Descaves Frederic
Guillot Yves
Sollier Luc
King Roy
McGuthry-Banks Tima
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ugine-Savoie Imphy
LandOfFree
Process for producing a foaming slag above a stainless steel... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing a foaming slag above a stainless steel..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing a foaming slag above a stainless steel... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2479035