Reduction of hematite (Fe2O3) to metallic iron (Fe) by CO in a micro fluidized bed reaction analyzer: A multistep kinetics study

The reduction kinetics of alpha-Fe2O3 to metallic iron by carbon monoxide at temperatures of 1023 to 1223 K was experimentally investigated in a micro fluidized bed reactor with in-situ mass spectrometer analysis of product gases. Results indicate that the overall reduction process could be separated into two parts that proceed in series. The first part represents a single-step reaction Fe2O3 -> Fe3O4 which takes place fast and covers the conversion from 0 to 1/9. The second part represents a two-step reaction Fe3O4 Fe which is a combination of two single-step reactions: Fe3O4 -> FeO and FeO -> Fe that occur in parallel and cover the range of conversions from 1/9 to 1.0. The reduction from Fe2O3 to Fe3O4 can be reasonably described by the first-order reaction model, while the reduction from Fe3O4 to Fe could be described by a parallel reaction model based on Johnson-Mehl-Avrami (JMA) equation. The apparent activation energies for Fe2O3 -> Fe3O4, Fe3O4 -> FeO and FeO -> Fe were determined as 30.60 +/- 0.75 to 52.99 +/- 0.78 Kj/mol, 52.44 +/- 0.10 to 80.83 +/- 0.12 KJ/mol and 45.74 +/- 0.25 to 92.12 +/- 0.27 Kj/mol, respectively, and were found to increase with increasing CO concentration. (C) 2017 Published by Elsevier B.V.