A techno-economic approach for magnetising roasting of iron ore composite pellet using conventional and hybrid microwave furnace

Abstract

The present study aims to enhance the iron ore fines through reduction roasting using a muffle and hybrid microwave furnace. The Taguchi statistical design was used to optimise the process variables such as temperature, time, and reductant concentration. The reduction roasting was followed by multi-pass low-mid intensity magnetic separation to treat the low-grade iron ore fines (Fe 44.53%, 40.13% silica). The results showed that the conventional reduction roasting at optimum conditions (800 °C, 60 min, 7% coal) produced a concentrate with 52.6% Fe grade and 77.3% recovery. The microwave roasting produced a concentrate with 53.06% Fe grade and 75.7% recovery at 750 °C, 2 min, and 7% coal as the reductant. The effect of both heating methods on compressive strength (CCS) and surface morphology was also studied. The results indicated that microwave heating resulted in a finer and more porous structure that improved the reducibility and ease of grinding. The techno-economic comparison showed that microwave reduction reduced the processing time by 85% and energy consumption by 73%. The study concludes that microwave heating followed by multi-pass magnetic separation can significantly improve the economic viability of exploiting lean iron ore fines.