Method for making steel

Abstract

A method is provided for producing steel from iron oxide-containing raw materials. The raw materials are initially converted, in a reduction furnace by direct reduction with a reducing gas, to a substantially metallized sponge iron. The metallized sponge iron is then melted with the addition of additives and possibly fine scrap in a melting vessel filled with a metal melt. Heat and carbon monoxide-containing exhaust gases are formed in the melting vessel due to the reaction of oxygen-containing gases with carbonaceous material. The heat is utilized in part to melt the sponge iron and the exhaust gases are utilized for the direct reduction. The melt is then transferred to a further vessel where it is further processed into steel by means of suitable metallurgical measures. In the process, the entire, strongly-heated exhaust gas from the melting vessel is caused to react in a reactor with (1) carbonaceous material, and with (2) water vapor and/or carbon dioxide. After suitable conditioning, this exhaust gas is utilized for the direct reduction of the iron oxide-containing raw materials. An exhaust gas is formed in the direct reduction furnace during the direct reduction, and part of this exhaust gas is conducted through a gas processing system and combined with the conditioned exhaust gas from the melting vessel to form the reducing gas used in the direct reduction furnace.