Reduction of Iron-Oxide-Carbon Composites: Part I. Estimation of the Rate Constants

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2008-12, Vol.39 (6), p.784-795
• Main Authors: Halder, S., Fruehan, R.J.
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; Applied sciences; BENCH-SCALE EXPERIMENTS; Carbon; CARBON DIOXIDE; CARBON MONOXIDE; Characterization and Evaluation of Materials; CHARCOAL; CHARS; CHEMICAL REACTION KINETICS; Chemistry and Materials Science; COAL; COAL GASIFICATION; Composite materials; Exact sciences and technology; FURNACES; Gasification; IRON ORES; IRON OXIDES; Materials Science; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; Oxidation; PELLETS; Production of metals; REDUCTION; ROTATION; SINTERING; SMELTERS; Structural Materials; Surfaces and Interfaces; Thin Films
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-008-9200-4

A new ironmaking concept using iron-oxide-carbon composite pellets has been proposed, which involves the combination of a rotary hearth furnace (RHF) and an iron bath smelter. This part of the research focuses on studying the two primary chemical kinetic steps. Efforts have been made to experimentally measure the kinetics of the carbon gasification by CO 2 and wüstite reduction by CO by isolating them from the influence of heat- and mass-transport steps. A combined reaction model was used to interpret the experimental data and determine the rate constants. Results showed that the reduction is likely to be influenced by the chemical kinetics of both carbon oxidation and wüstite reduction at the temperatures of interest. Devolatilized wood-charcoal was observed to be a far more reactive form of carbon in comparison to coal-char. Sintering of the iron-oxide at the high temperatures of interest was found to exert a considerable influence on the reactivity of wüstite by virtue of altering the internal pore surface area available for the reaction. Sintering was found to be predominant for highly porous oxides and less of an influence on the denser ores. It was found using an indirect measurement technique that the rate constants for wüstite reduction were higher for the porous iron-oxide than dense hematite ore at higher temperatures (>1423 K). Such an indirect mode of measurement was used to minimize the influence of sintering of the porous oxide at these temperatures.