Enhanced Reduction of Carbon-Iron Ore Composite Briquettes under Varying Pressing Forces via Direct Microwave Heating

This study uses direct microwave heating to investigate the direct reduction process in carbon-iron ore composite briquettes under varying pressing forces. The composite briquettes, made from magnetite iron ore concentrate, anthracite coal, and bentonite as binder, were pressed at 1-ton, 2-ton, and 3-ton loads and then subjected to microwave irradiation. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed to analyze the phase composition and structural changes. The results show that the 1-ton briquettes exhibited predominantly metallic Fe with minor fayalite and FeO phases, whereas the 2-ton and 3-ton samples displayed increased fayalite formation. Notably, re-oxidation occurred in the 2-ton and 3-ton samples, as indicated by the presence of Fe₃O₄. The higher pressing forces caused reduced air permeability and lower CO diffusion efficiency, hindering the reduction process. These findings highlight the influence of compaction pressure on the reduction process and the potential of microwave heating as an energy-efficient alternative in ironmaking.