Development of Fluxed iron oxide pellets strengthened by CO2 treatment for use in basic oxygen steel making

Abstract

Lump lime is presently being used as a fluxed material in basic oxygen steel making process. However, problems are often encountered in operation due to its high melting point, poor dissolution property, fines generation and hygroscopic property. Binary CaO–Fe2O3 has a eutectic point (1200°C) with 22% CaO. An agglomerate of lime and iron oxide under BOF condition would thus generate low melting oxidizing slag at the beginning of blow and would facilitate refining process. In this study, lime fluxed iron oxide pellet has been prepared using waste iron oxides and its strength was developed by CO2/CO2 containing gas treatment at room temperature, while no separate binders has been used. Industrial waste gases, say, blast furnace gas (BFG) may suitably be used as CO2 source. The pellet making process parameters such as composition of pellets, grain size of iron ore fines, treatment conditions etc. have been optimized through physical characterization like cold compressive strength, drop strength, abrasive resistance etc. Up to around 30 kg/pellet cold compressive strength, around 150 drop strength and excellent abrasive property have been achieved.