In situ observation of iron ore particle reduction above 1373 K by confocal microscopy

The reduction behavior of single iron ore particle was investigated at high temperatures (above 1373 K) with CO/CO₂ mixture. A high-temperature laser scanning confocal microscope for in situ observation and a vertical quenching furnace for offline characterization were designed. The reduction process of ore particles at different temperatures and in different atmospheres was videoed using the confocal microscope. In the temperature range studied, the transformation of Fe₂O₃–FeO firstly occurred in the ore particles, and there was no metallic iron until the ore particles completely converted to FeO phase. During the formation of FeO phase, its crystal lattice transforms along the most close-packed direction of its close-packed plane (111). The gangue-rich area firstly melts during reduction around 1573 K. Above 1673 K, the iron ore particles melt and form spherical liquid drops with metallic iron in the center. The gas-based reduction behavior of iron ore particles above 1373 K is deduced and graphically presented.