Reduction kinetics of commercial haematite pellet in a fixed bed at 1123–1273 K

Abstract

In the present study a model for future use in the modelling of moving bed direct reduction reactors has been developed. The model of a fixed bed reactor for the production of sponge iron from haematite incorporates both heat- and mass-transfer, as well as the chemical reduction rate. The model results were compared to the experimental data obtained from a lab scale reactor in the temperature range 1123–1273 K, as well as to the output from a simple model assuming isothermal conditions. The H₂/CO ratio (β) of the reducing gas was in all cases varied from 0.8 to 2.0. Overall the non-isothermal model developed permits a more accurate representation of the experimental data than the isothermal estimates, with a typical discrepancy of only 1.3%.

Keywords:

• Fixed bed
• Shrinking Core Model
• Gas-solid reaction
• Heat transfer
• Direct reduction
• Kinetics
• Haematite

Acknowledgements

The authors would like to thank the CK-lab of LKAB in Malmberget, Sweden, for the use of the TGA (Thermal Gravity Analysis) furnace. The supply of KPRS pellets from LKAB in Kiruna, Sweden, is gratefully acknowledged. The present study was supported by BP and Nordland fylkeskommune in Norway, and LKAB in Sweden.