Utilization of Biomass Pellets in the Iron Ore Sintering Process

Abstract

The Iron and Steel industry plays a vital role in global economic growth, consuming a significant portion of the annual industrial energy, primarily sourced from fossil fuels. Sinter making is a crucial process in Ironmaking, having 10% energy consumption share of the entire Steel industry with 78% of it coming from coke breeze thus contributing significantly to greenhouse gases, SOx and NOx emissions. Substituting fossil fuels with biomass, a clean and renewable energy source, is an attractive option for carbon-neutral iron ore sintering. In the present study, an attempt was made to utilize biomass pellets (called Biopellet) for sintering process by varying it from 0 to 4% of the total raw mix blend as a solid fuel substitution. The resulting sinter was evaluated based on productivity, product yield, sintering time, and tumbler index, while the exhaust gas emissions were analysed for NOx and SOx, emissions. With an increase in biopellet the sintering time increased from 25.30 to 31 min, with a drop in sinter productivity from 1.78 to 1.09 t/m²/hr. The calorific values of biopellet, was around 66% of coke breeze. The maximum sintering temperature reduced due to evaporation of volatile matter from the biopellet ahead of the flame front. The increased biopellet proportion reduced the sinter product yield from 82 to 70%, owing to lower heat input from the biopellet. The strength of the sinter however was more or less maintained at around 65% for all the trials. The presence of biopellet affected the exhaust gas composition, with a reduction in overall NOx and SO₂ emissions. Despite the trade-offs, such as decreased sinter yield, biomass pellets are an attractive alternative for achieving sustainable steel production due to their ability to reduce emissions.