Iron ore reduction using agricultural waste biochar with different carbon to oxygen ratios

Background: During iron production ferric oxide is reduced to iron, with carbon used as the reducing agent. Traditionally, coke was used as the carbon component, which became a crucial raw material in the iron and steel industry after the industrial revolution. However, coke is the most significant contributor to CO2 emissions due to the source of heat and reducing agent. Thus, shifting to low carbon energy systems, such as those based on biomass, is challenging. Therefore, in this study, we employed the mushroom cultivation residue char (MCRC) as a reducing agent to investigate the feasibility of replacing coke in the production of metallic iron. Methods: After carbonization at different temperatures (500 degrees C, 700 degrees C and 900 degrees C), mushroom cultivation residue char (MCRC), were used as a reducing agent in the production of metallic iron. To create the composite pellets, the MCRCs were individually mixed with iron ore at different carbon to oxygen ratios (C/O) (0.7, 0.8 and 0.9) and 1 % of bentonite. The reduction process was undergoing in the electric muffle furnace at different high temperatures (1,000 degrees C, 1,200 degrees C and 1,300 degrees C) to investigate the biomass C/O ratios required for efficient iron production. Significant findings: The results show that 0.8 was selected as the optimal C/O ratio for mushroom cultivation residue char (MCRC) to be used as a reducing agent. Its metallization rate can reach 31.99 %. The results also indicate that the carbon and volatiles in MCRC play a key role in iron making production using such biochar pellets. In conclusion, MCRC can be used as a reducing agent to increase the sustainability of iron production and reduce agricultural waste.