Use of slag ferromanganese to deoxidize low-carbon rimming steel

Abstract

The Karaganda Metallurgical Combine has developed and introduced a technology for deoxidizing low-carbon rimming steel (including steel for use in tinplate production) which employs slag ferromanganese. The technology includes refining of the steel in 300-ton converters from phosphorus pig iron (1-1.3% P) by the double-slag process and deoxidation in the ladle during tapping with high-carbon ferromanganese containing up to 1.5% Si. Aluminum in amounts up to 100-150 kg/ton steel is added to the ladle, the exact amount depending on the carbon content of the metal prior to tapping. If necessary to keep the manganese content of the finished steel in the range 0.320.38%, ferromanganese is also added during blowing of the metal with inert gas on the finishing unit. The steel is teemed through a 60-ram-diameter nozzle into ingots weighing 16.3 tons. When the metal is deoxidized in the ladle, assimilation of silicon from the ferromanganese averages about 15%. As a result, the silicon content of the steel increases to 0.008-0.12%. Shown below are processing and quality indices of heats of steel 08kp deoxidized with ferromanganese containing different amounts of silicon: