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

Abstract

The reduction kinetics of α-Fe2O3 to metallic iron by carbon monoxide at temperatures of 1023 to 1223K 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±0.78KJ/mol, 52.44±0.10 to 80.83±0.12KJ/mol and 45.74±0.25 to 92.12±0.27KJ/mol, respectively, and were found to increase with increasing CO concentration.