Recycling red mud to develop a competitive desulfurization flux for Kanbara Reactor (KR) desulfurization process

One of the industrial wastes, red mud, was assessed as an additive to lime, as a new desulfurization flux for the hot metal in the steelmaking process. Since typical red mud contains some amount of iron oxide, a preliminarily reduced red mud was mainly investigated. Pre-reduction of the red mud and execution of mechanical stirring to the hot metal were effective to enhance desulfurization efficiency (extent and rate of the reaction). However, adding more than 20 pct of red mud in the lime/red mud (pre-reduced) flux did not increase the desulfurization rate. In order to assess the desulfurization efficiency in a more quantitative manner, a "DeS Index" was defined as: [Formula: see text] . This takes into account the extent, rate, and cost of the desulfurization simultaneously. With this index, it was found that the presently developed red mud (pre-reduced)/lime mixtures showed almost similar desulfurization efficiency compared with those of commercially used desulfurization fluxes. It was even better than a typical lime/fluorspar mixed flux, which is now prohibited from being used in many companies due to its environmentally harmful character. It is emphasized that the desulfurization efficiency should be assessed under the mechanical stirring in order to be used in the KR type desulfurization process.