Effect of different forms of carbon on the reduction behaviour of iron ore-carbonaceous material composite pellets in multi-layer bed rotary hearth furnace (RHF)

Abstract

ABSTRACT The present study investigates the effect of different forms of carbon in various coal and char-based composite pellets on reduction kinetics in a laboratory-scale multi-layer bed rotary hearth furnace at 1250°C. A novel plot showing the variation of DOM (degree of metallization) against DOR (degree of reduction) demonstrated the role of heat and mass transfer in the reduction process irrespective of layers and type of pellets. Char-based composite pellets exhibited higher reduction efficiency than coal-based pellets, even at comparable fixed carbon levels, attributed to micro-porous morphological features, and less fayalite formation in the char-based pellets. Top layer registered the maximum extent of reduction, and middle layer registered the minimum. Bottom layer also showed comparable reduction to the top layer due to more active volatile contribution at the bottom layer. Formation of fayalite at the top layer restricted the maximum extent of reduction beyond 80%.