Gas–Solid Reaction Kinetic and Mechanism Between Fe₃O₄ and CH₄

Iron and steel have a significant economic and application importance, therefore the reduction of iron oxides is of interest to many researchers. There is a high-energy demand for steel and iron making industries, and it is crucial to address the kinetics of reactions on natural gas as a source of energy and reducing agent for most steel companies. In this thermogravimetric study, the reaction kinetics of Fe₃O₄ fine particles by using CH₄ reduction has been investigated at temperatures ranging from 800 to 1100 °C which have been compared with the results obtained from concentrate reduction by H₂ and CO. Different models have been assessed to obtain the governing mechanism and kinetics parameters of this reaction. Unlike H₂ and CO reducing agents, the sintering phenomenon increases the rate of CH₄ reduction at temperatures more than 900 °C. Dependency of the reaction rate on the amount of Fe₃O₄ is classified as first-order reaction and this dependency on their particle size is a power function with a − 1.871 power. The reaction rate also is considered a power function of CH₄ concentration with − 4.236 power. The reaction activation energy estimated equal to142.5 kJ mol⁻¹.