A study on separation of Mn and Fe from high-alumina ferruginous manganese ores by the carbothermal roasting reduction process

Carbothermal reduction followed by magnetic separation has been recognized as an effective recovery strategy to achieve separation of Mn and Fe from ferruginous manganese ores (Fe-Mn ores). However, it is difficult to improve the recovery of manganese more than 85% by changing carbothermic roasting reduction and magnetic separation. This work clarified the underlying reason for the poor separation with the magnetic separation process and proposed a promising process for the recovery of Fe and Mn from Fe-Mn ore. The effect of operating variables on recovery and separation of Mn and Fe from Fe-Mn ore is initially investigated during the carbothermic reduction roasting process followed by magnetic separation to reveal the underlying reason for the poor separation from Fe-Mn ores. Then, the stepwise reduction behaviors of the MnO-Fe 2 O 3 and MnO-Fe 2 O 3 -Al 2 O 3 systems were investigated to clarify that the formation of composite oxide Mn 1−x Fe x O (0 < x < 0.497) and hercynite (FeO·Al 2 O 3 ) directly caused the poor separation of Fe and Mn from high-alumina Fe-Mn ores. Then, the stepwise reduction roasting behaviors of Mn 1−x Fe x O and FeO·Al 2 O 3 were investigated by XRD, SEM-EDS and XPS analysis. After adjusting the experimental parameters, iron-rich products with a Fe recovery of 94.31% and a grade of 85.21% and manganese-rich product with a Mn recovery of 90.05% and a grade of 54.35% are obtained. The mass ratio of Mn/Fe increased to 8.5 in the manganese-rich product.