8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Pellets were introduced into the Blast furnaces at Tata Steel Jamshedpur post the commissioning of pellet plant in the year 2012. The new burden mix (sinter, ore and pellet) offered an opportunity to produce sinter using a new flux regime which permitted flexibility in ore mix and resulted in change of sinter properties. A strategic decision was taken to produce pellets at acidic/minimum flux regime implying that major portion of the flux requirements of blast furnace would be met through sinter. The major shift in sinter chemistry was the increase in CaO content in sinter to >12% based on proportion of sinter and pellet in burden mix in the blast furnace. Simultaneously, fine ore mix to sintering was switched over from higher fines from Noamundi source to higher fines from Joda source. Joda ore fines has lesser amount of super-fines size (-0.15 mm) in granulometry and lesser goethite content in lattice structure compared to Noamundi ore fines. These key strategic changes to operate sinter making in new high flux regime and higher use of Joda ore fines resulted in improvement of sinter quality parameters like Reduction degradation index (RDI) and Reducibility index (RI) as well as 15% (approx.) reduction in fuel rate for sintering. The improved sinter properties were correlated with presence of higher amount of calcium ferrites and Silico ferrites of calcium and alumina (SFCA) phases in matrix of sinter microstructure.