High-temperature meltdown characteristics of DRI-flux mixture in a melter-gasifier

The slag formation mechanism in the melter-gasifier was examined by the mel tdown test for DRI-additive-ash mixed bed under load and by analysis for th e slag taken from the actual furnace of the two-step ironmaking process. Fo r the slag phase analyses, chemical analysis, SEM-EDS and XRD pattern analy sis were employed. The primary slag originated from the gangue in DRI was h omogeneous. Partially-melted secondary slag consisting of dicalcium silicat e with dissolved FeO was formed under rather higher CaO/SiO2 basicity compa red to that of tapped slag. Then, these slags reacted with bottom ash resul ting in the homogeneous tertiary slag with the dissolved FeO. Finally, the final slag, similar to tapped slag, was collected on the top of the metal p ool. The slag had CaO/SiO2 slightly greater than 1 in the hearth of the mel ter-gasifier.