Magnetite surface morphology during hematite reduction with CO/CO2 at 1073 K

The morphology of the magnetite phase that formed during the hematite/magnetite reduction process was studied. A very dense hematite ore of very high grade iron content (Fe = 69%) was used. Annealed ore specimens of about 2 g and 5 × 5 × 1 mm size were polished and reduced with 20%CO–80%CO2 gaseous mixtures of total gas flow rate 1 L/min at 1073 K. The morphological observation of the surface of the specimens and its cross-section after reduction was detected by SEM. The initial formation of magnetite phase nuclei was detected as needles in shape. These needles of about 500–1000 nm diameter and length 10–15 μm come in a random distribution in the reduced surfaces. These needles are accumulated after forming a large centered area of a porous magnetite phase inside each surface grain.