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Development of Prefused Synthetic Flux for Basic Oxygen Steel Making through Micro-Pelletization and Sintering of Iron Oxide Fines



Calcined lump lime is used as flux material in basic oxygen furnace (BOF) steel making. Due to its high melting point and poor dissolution property, slag formation takes a long time. Since, Fe2O3–CaO has eutectic melting point of 1230°C at the composition of 22% CaO, material containing Fe2O3 and CaO can easily melt and form basic oxidizing slag at the very beginning of the blowing to make the refining process faster. A partially prefused synthetic flux in combination of mainly CaO and Fe2O3 has been prepared through micro-pelletization and sintering (MPS) of waste iron oxide fines generated in steel plant. The fines were converted to strong micropellets to make it suitable for sintering. Cold handling strength in micropellets was imperted by a novel CO2 treatment technique at room temperature and cold compressive strength up to 9 kg/pellet with a good abrasion resistance could be observed. The sintering of the developed micropellets was carried out without using coke breeze and produced sinter showed good handling strength, resistance to thermal shock and weathering, low softening temperature and thus qualifying it as a suitable alternate flux material for BOF towards fast formation of oxidizing and basic slag.