Metallgesellschaft Aktiengesellschaft

Sms Demag Ag

Bernt Rollinger

Johann Reichel

Stefan Lemke

Karl Reiner Götzinger

The invention relates to a method for producing stainless steels, in particular steels containing chromium and chromium-nickel. The method is carried out in a melting device containing a metallurgical vessel, or in a melting device () containing at least two vessels () for supplying a steel-casting installation, an electric arc furnace process () and an air-refining process taking place alternately in the two vessels (). To improve the efficiency of a method of this type, the aim of the invention is to carry out a reversible treatment of unreduced converter slag in the electric-arc furnace mode. To achieve this, in the first treatment stage, the slag () with a high chromium content is melted together with the added charge, the slag is then reduced during the melting process with the silicon and carbon under favorable thermodynamic conditions of the arc, once the slag has reached a minimum temperature of 1,490&#xb0; C. and the slag is subsequently removed. The air-refining process is then carried out, during which the carbon content is reduced to a value of less than 0.9%. The metal slag () is tapped at a tapping temperature of between 1,620 and 1,720&#xb0; C., the unreduced slag () with a high chromium content from the air-refining process remaining in the treatment vessel.

Method for producing stainless steels, in particular high-grade steels containing chromium and chromium-nickel

The process for making a refined molten steel includes melting preheated solid iron sources and solid carbon sources in a melting vessel with heat generated by electric arc to form a carbon-containing molten material and then melting other preheated solid iron and carbon sources in the carbon-containing molten material by heat generated by combustion reaction in the melting vessel. In the combustion reaction oxygen is fed into the molten material through nozzles located in the melting vessel below the surface of the molten bath. The exhaust gases formed in the melting vessel are used to preheat the solid iron sources and then are burned in an afterburner to reduce pollution. An apparatus for performing the process is also described.

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Taunusstein, Germany

Bernt Rollinger