Development of Blowing Process for High Manganese Hot Metal in BOF Steelmaking

Abstract

Steel production in Indian steel plants is affected by non-availability of good quality iron ores. This increases the thrust on developing technologies and processes to utilize low grade ores. A large quantity of high MnO iron ores have been lying at various mines unutilized by steel plants. Hot metal produced using these ores results in Mn (wt%) greater than 1 % and lead to process abnormalities and high refractory wear in converters. To utilize such ores, JSW Steel, experimented with high Mn hot metal in 130 T converters and successfully developed a blowing process. By optimising slag properties and blowing patterns through a series of tests in a 130-ton converter, a double-slag method was developed to blow >1 % Mn (wt%) content hot metal. The new blowing practice utilized the manganese humpback phenomenon to selectively treat high Mn and its efficient removal during steelmaking. It was found that the slag composition and de-slagging time is the most critical parameter in the new double slag blowing practice. This new process had helped JSW steel to utilize inferior ores successfully.