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Modelling of DRI Processes with Two Simultaneously Active Reducing Gases
Author(s) -
Kolbeinsen L.
Publication year - 2010
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201000144
Subject(s) - syngas , magnetite , direct reduced iron , hematite , pellets , wüstite , coal , carbon monoxide , iron ore , chemical looping combustion , natural gas , hydrogen , tonne , methane , water gas shift reaction , reduction (mathematics) , iron oxide , chemistry , waste management , materials science , fluidized bed , metallurgy , engineering , catalysis , composite material , biochemistry , organic chemistry , geometry , mathematics
The concept of DRI is understood as reduction of iron ore (oxide) without the occurrence of a liquid phase, and where the means of reduction is either coal or natural gas. This method for making iron has existed since the Iron Age, but had its renaissance in the 1960s. Today's DRI production is of a magnitude of 60 million metric tons a year, and is rapidly growing. The MIDREX® and HyL® processes are based on reduction in a packed bed (shaft furnace), something that requires the ore to be pelletized. The reduction of fine grain ore directly, typically fluidized beds with multiple reactors in series like in the FINMET® process, constitutes another process family. In both cases the gas doing the reduction‐work will be a synthesis‐gas (SynGas/SG), but with variations in the H 2 /CO‐ratio from process to process. Use of the top‐gas from the reduction as an oxygen source in the SynGas generation is common. Mathematical modelling is considered essential for development and optimization of such processes. Reduction of single pellets can be described using various models, e.g. the well known Shrinking Core Model (SCM). The classical SCM needs to be modified both with respect to the solids to include the intermediate products magnetite and wüstite that exist between hematite and metallic iron, but also with respect to the gas to handle two different reactants; hydrogen and carbon monoxide, and should also include the possible internal gas reactions like the water gas shift reaction (WGSR). The use of oxygen potentials can replace gas compositions in modelling of such systems. In this paper a model for the reduction of a single iron ore pellet is described; and further a description is given of how such a model is incorporated into a full process model as well as experimental methods of how to determine model parameters.