New understanding on reduction mechanism and alloying process of rich manganese slag: Phase formation and morphological evolution

A new understanding of the reduction mechanisms of ferruginous manganese ores for ferromanganese alloy smelting was reported, and this new understanding was used to produce excellent ferromanganese alloys. To fulfill this objective, the effects of the operating variables on smelting ferromanganese alloys were initially investigated. The formation mechanisms and reduction reaction behaviors of olivine (Ca x Fe y Mn 2-x-y )SiO 4 , spinel (Ca x Fe y Mn 1-y-x )Al 2 O 4 , gehlenite (Ca x Mn 2-x )SiAl 2 O 7 and wüstite Mn x Fe y Ca 1-x-y O systems were systematically discussed to understand the phase transformation and reconstruction of manganese ore at high temperatures. The spinel (Ca x Fe y Mn 1-y-x )Al 2 O 4 that originated from (Fe y Mn 1-y )Al 2 O 4 was converted to CaAl 2 O 4 and then further reduced to ferromanganese alloys. A similar expression was applied to describe how the reduction mechanism of olivine (Ca x Fe y Mn 2-x-y )SiO 4 that originated from (Fe y Mn 2-y )SiO 4 was converted to Ca 2 SiO 4 . In addition, the importance of the formation of gehlenite (Ca x Mn 2-x )SiAl 2 O 7 and wüstite Mn x Fe y Ca 1-x-y O phases in smelting ferromanganese alloys was discussed and clarified in detail. Based on the findings, recommendations are provided for the theoretical basis and technical support of smelting ferromanganese alloys.