Iron Carbonate Beneficiation Through Reductive Calcination - Parameter Optimization to Maximize Methane Formation

Direct iron carbonate reduction through reductive calcination in a hydrogen atmosphere is a high-potential candidate for environmentally benign pig iron production. In addition to the direct formation of elemental iron in one reaction step, carbon dioxide is only partially released from the carbonate. Instead, carbon monoxide, methane, and higher hydrocarbons form as gaseous reaction products. The experimental study described here is based on Mg-Mn substituted iron carbonate ore. First, the chemical thermodynamics of the reductive calcination of iron, magnesium, and manganese carbonate are discussed. The influence of temperature and pressure on equilibrium conversion is reviewed together with the accessible products. Results for the reductive calcination of mineral iron carbonate in a tubular reactor setup are presented. The methane yield was optimized via statistically planned design of experiments. The gauge pressure and temperature showed a statistically significant effect on the total iron carbonate conversion, as well as on carbon monoxide, and methane yield.