Biochar as a sustainable alternative to conventional carbon additives in iron ore pelletization

Abstract

The present research highlights the growth of India’s iron and steel industry and the increasing demand for energy-efficient iron production methods. The study investigates the use of biochar as a sustainable alternative in the iron ore pelletization process, with the goal of reducing dependence on traditional additives such as coke fines. The evaluation of pelletization performance involved incorporating an organic binder and biochar derived from rice straw as substitutes for bentonite and coke fines, respectively. Various pellet formulations were tested at different induration temperatures to assess their cold compressive strength (CCS), porosity, and metallurgical properties, including the reducibility index (RI), swelling index (SI), and reduction degradation index (RDI). The results indicate that biochar-based pellets exhibit higher CCS and porosity compared to conventional pellets, achieving optimal performance at a lower induration temperature of 1280 °C with 0.5 wt% of both the organic binder and biochar. Additionally, the presence of biochar enhances porosity and reducibility while preserving acceptable swelling behaviour. Microstructural and phase transformation analyses further support these findings, shedding light on the mechanisms of pellet consolidation. Overall, the study suggests that biochar, combined with an organic binder, can serve as a viable renewable carbon source, offering an environmentally friendly alternative for sustainable iron production.