Reduction Behavior and Structural Evolution of Iron Ores in Fluidized Bed Technologies—Part 2: Characterization and Evaluation of Worldwide Traded Fine Iron Ore Brands

Abstract

The reduction of iron ore fines by means of fluidized bed technology has become an alternative route of ironmaking. To investigate the reduction behavior of fine ores and to improve fluidized bed processes, a lab scale fluidized bed facility is installed. The reactor is charged with different kinds of fine ores. The reactors get fluidized by a reducing gas mixture containing H2, H2O, CO, CO2, CH4, and N2 in variable range. Additionally, a sampling system is installed, which enables the sampling of bed material during reduction. All samples are analyzed regarding their grain size distribution, chemistry, and morphology. The comparison of the raw input ore with the reduced ore—bed samples during the tests and final material—leads to a new way of fine ore characterization. After the determination of a standardized process, globally traded iron ore fines are tested under the same process conditions. The results enable the validation of the morphological evolution of different iron ore types and brands (hematitic, magnetitic, and limonitic) during the reduction with CO‐rich reducing gas in fluidized bed processes. Further investigation on the structure and porosity of the different phases is done to evaluate the relation to reduction rate and final reduction degree.