Structure evolution of a magnetite iron ore/carbon composite pellet during solid-state reduction under microwave heating

Abstract

In the present study, the structure evolution under direct reduction of a Minh-Son magnetite iron ore/carbon composite pellets in a microwave-heating kiln under different microwave wattage of 60 and 90 % (with the firing time from 15 to 120 min.) was investigated. The microstructure of the pellets was characterized by scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction (XRD). The phase formation was indexed using MDI Jade from the peaks matching the reference sample. At the microwave’s wattage of 60 %: the wustite (FeO) has appeared after firing time of 60 min., the metallic iron and fayalite have appeared in the reduced samples after firing time of 90 min. to 120 min. with retained phases of Fe203, Fe304, FeO and Si02– While at the microwave’s wattage of 90 %, the metallic iron has appeared in the reduced samples after firing time of 30 min. to 120 min and fayalite has appeared in the reduced samples after firing time of 60 min. to 120 min. The final reduced pellet, under microwave’s wattage of 90 % and firing time of 120 min., shows the only phases of metallic iron and fayalite according to the XRD resolution. The present work could provide a scientific understanding to illustrate iron ore/carbon composite pellet behavior during solid-state carbothermic reduction under a microwave-heating.