Microstructural Changes and Kinetics of Reduction of Hematite to Magnetite in CO/CO2 Gas Atmospheres
The microstructures of porous magnetite formed on gaseous reduction of dense hematite have been examined using high-resolution scanning electron microscopy. It has been shown that cellular pores are formed on reduction in the temperature range 573 K to 973 K (300 °C to 700 °C). Dendritic shaped gas pores are formed on reduction at temperatures between 1073 K and 1273 K (800 °C and 1000 °C). The apparent chemical reaction rate constant for the reduction of hematite to magnetite in CO/CO2 gas mixtures has been derived from measurements of product thickness against reaction time; the rate constant is described by the relation φCO = 0.232exp(76,000/RT) µm s−1 atm−1.
The authors would like to acknowledge financial support for this project from the Australian Research Council (ARC) Discovery program. Thanks to Suping Huang and Hong Wee Kor, Pyrometallurgy Innovation Centre (PYROSEARCH), for their support for the experimental work. The authors also acknowledge the facilities, and the scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy and Microanalysis, The University of Queensland.
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