Kinetics of Manganese Reduction Comparing Synthetic Slags and Ores for Ferromanganese Production

Abstract A fundamental understanding of MnO reduction is important to ensure optimal conditions to produce ferromanganese alloys. In this study, MnO reduction at 1550 $$^{\circ }$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C was studied using synthetic slags and ores of varying basicity in a CO-Ar atmosphere. The synthetic slags were of 0.6, 0.8, and 1 basicities. The basicity of Comilog ore was adjusted by adding CaO. Results from the thermogravimetric analysis of synthetic and ore slags confirm that during the reduction of primary slags, the rate of reduction would be constant in the presence of solid MnO phase in the slag. An increase in the rate of reduction would be observed close to the liquidus MnO content when the slag is transitioning from a two-zone to a single-phase slag. After the increase, the rate of reduction will gradually lower in the single-phase liquid slag due to lower activity of MnO. The synthetic slags were found to have slightly higher reactivity compared to ores. It was also seen that in the multiphase area of the reduction, the size of the solid MnO particles increased with time.