Marcos Contrucci

Abstract:

For more than two centuries now the gas-solid smelting mode has been the dominant way to produce Iron from its ores, in the Blast-Furnace process. The main reason for this long lasting dominance was that iron-ores were found in nature as stones. By mid XX Century, stones got scarce so fine iron-ores had to be used. Because of the very nature of Blast-Furnaces smelting mode, fine iron-ores should be made into lump form to suit the size requirements of the Blast-Furnace burden. Producing artificial stones, thru high temperature sintering of fine iron-ores became common practice, followed soon by pelletizing of finer fractions usually resulting from concentration of poorer iron-ore reserves. The consequence of attaching to the historical smelting mode was that more capital and energy intensive steps had to be added to the road to steel. Nonetheless, in the other hand, charge preparation was key to improve the efficiency of Blast-Furnaces and thus sinter and pellets became classical burden materials. But the gas-solid mode is inherently a slow process since it implies the penetration of the reducing gas molecules into the solid stones of the charge. A high residence time results, what translates into the need of high stacks for the burden, hence the need for high strength coke. Coking plants, thus became part of the integrated complexes, adding even more capital and energy intensive units. In our century, the need to reduce CAPEX and OPEX in Steelmaking and an urge to abate its impact on the environment became clear. <br />This paper deals with the basics of Self-Reduction smelting mode and how and why it will change Iron making forever and for the best. Starting by a review of the well established cold bonded Self-Reduction agglomerates production ways and proceeding to a detailed thermo-chemistry analysis behind the extremely fast smelting capabilities of the built-in reactions within them, the paper proceeds to an explanation on why such simple reasons can slash CAPEX, OPEX and emissions in Iron making to unprecedented levels and, just as important, how and why existing Blast-Furnaces can be retrofit to accommodate to the self-reduction mode of reactions. Follows an in depth reflection on the raw-materials and supply chain opportunities the self-reduction mode brings about, when new logistics friendly products, out of this simple innovative mode, shall impact the Iron-Units supply chain and the very structure of the Mining and Steel business worldwide. <br />Keywords: Ironmaking