Metallization and Carburization Kinetics in DR Shaft Furnaces: The METCARB Model

The production and consumption of Direct Reduced Iron (DRI) are continuously increasing, as a consequence of the impact of shale gas extraction technology on the Natural Gas (NG) market. Considering this context, DRI may improve the Blast Furnace (BF), Electric arc Furnace (EAF) and LD converter’s productivities and consequently their competitiveness. In this work the results of a cooperative research conducted by PUC-Rio University and a Brazilian mining company are presented. Laboratory-scale simulation tests, using DR commercial pellets and typical industrial operational parameters of a benchmarked DR shaft furnace, were conducted and planned using statistical and factorial analysis. In the simulated experiments, the following three regions of the DR shaft furnace were considered: Reduction Zone (RZ), Transition Zone (TZ) and Cooling Zone (CZ). Three stages were considered in the research development: (i) the reactions and equations concerning pellet metallization and Carbon precipitation were analyzed; (ii) experiments focused on the definition of the carburization kinetic equations occurring in the Transition and Cooling zones, and finally, (iii) aimed to develop the “METCARB” model, a computational program conceived to simulate mathematically the metallization and carbonization reactions along the height of the furnace. In conclusion, a comparison is made with industrial results in order to validate the resulting “METCARB” model.