Method for producing foamed slag on high-chromium melts in an electric furnace

Abstract

The invention relates to a method for producing foamed slag on high-chromium steel melts in an electric furnace, whereby a mixture consisting of a metal oxide and carbon is introduced into the furnace, the metal oxide in the slag is reduced by the carbon, and the gases created in the slag form bubbles which thus foam up the slag. In order to be able to control the gas formation and thus the foaming process, the mixture consisting of a metal oxide and carbon and optionally an iron carrier is introduced as preforms, such as pellets, which are compressed and / or provided with a binding agent. The gas formation can be controlled in terms of location, type and time, by adjusting the characteristics of the pellets, especially the density and / or compression characteristics thereof.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application is a Continuation of U.S. patent application Ser. No. 10 / 557,190, filed Nov. 18, 2005, which is a 371 of International application PCT / EP2004 / 004312, filed Apr. 23, 2004, which claims priority of DE 103 23 505.1, filed May 24, 2003, the priority of these applications is hereby claimed and these applications are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The invention concerns a method for producing foamed slag on high-chromium steel melts in an electric arc furnace, wherein a mixture of a metal oxide and carbon is introduced into the furnace, the metal oxide is reduced by the carbon in the slag, and the resulting gases bring about the foaming of the slag by bubble formation.[0003]In the operation of electric arc furnaces, the charge, i.e., mainly scrap, and alloys are melted by the electric arcs of the electrodes, which extend downward into the furnace shell. The slag fulfils not only its pri...

AI Technical Summary

Benefits of technology

The invention provides a method for controlling the foaming reaction in a furnace by using compressed pellets made of metal oxide and carbon, which can be adjusted to control the gas evolution and the starting point of reaction. The density of the pellets is adjusted to ensure that they float in the slag near the metal-slag phase boundary, preventing carburization. The iron carrier added to the mixture helps to adjust the pellet properties, and a slag thinner can be added to counteract the tendency of chromium-containing slags to become viscous. Additionally, reducing agents like silicon and aluminum can be added to control the chromium oxide content of the slag and improve foaming.

Problems solved by technology

Furthermore, the pellets should have a density or a degree of compaction that causes them to disintegrate uniformly and slowly, so that the foaming reaction occurs uniformly and over a relatively long period of time.

In addition, it is possible to cause the reactions to occur with a time delay by using even higher pressure compaction.

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