Thermal reduction of steel-making secondary materials: I. Basic-oxygen-furnace dust

Abstract

A study of the thermal reduction of basic oxygen furnace (BOF) dust was carried out using simultaneous thermogravimetry, differential thermal analysis and Fourier transform infrared spectroscopy. X-ray diffraction, chemical and mineralogical analyses were also used. BOF dust, which mainly consists of higher iron oxides (magnetite and hematite), is the largest by-product flue waste released in the integrated steel-making process. Blast furnace (BF) dust, a carbon–iron-rich flue waste released in the iron-making process, was used as a reductant. Both of the starting materials were examined individually using the same techniques. The effect of the reaction atmosphere, the amount of reductant and the temperature were examined. The results indicated that, at 1300°C in inert atmosphere, a partial reduction of the contained iron oxides takes place with 20% reductant in the mixture. With 50% reductant, under the same conditions, a complete metallization of the iron oxides in the dust takes place. The thermal analysis results were verified by identifying the reaction products as well as the gaseous species evolved during the reduction reactions.