Pre-Heating Manganese Ore in a Pilot-Scale Rotary Kiln

The production of high carbon ferromanganese alloys is traditionally carried out by smelting oxidized ores in electric furnaces using carbonaceous material as reducing agent, generating CO2 emissions which contribute to climate change. The actual carbon consumption is not optimal, there is an overconsumption linked to an incomplete decomposition and prereduction of manganese oxides inside the submerged arc furnace (SAF), where the reactions kinetics can be difficult to control. In the PREMA project, the considered solution consists in optimizing ores heating and pre-reduction before the SAF in a separate unit in order to reduce its electricity consumption as well as its CO2emissions. After preliminary tests in a lab scale rotary kiln have been performed, the pre-heating of raw materials in a continuous pilot scale rotary kiln was studied during a campaign at Eramet Ideas. The objective was to study the kinetics of thermal decompositions of two different Mn ores. The evolution of the ore composition was assessed with chemical analysis and by the study of the phases thanks to the XRD and Qemscan analyses.