Study on the influence of Al2O3/SiO2 on the kinetics in the prereduction zone during high carbon ferromanganese production using basic south african manganese ores

During the production of high carbon ferromanganese, the feed undergoes different stages of reduction. Three main zones were assumed instead of traditional four. The influence of phases formed during pre-reduction have a gigantic impact on the kinetics of the quality of the final products. In the current investigation, basic South African manganese ores were used. Two different fluxes were tested namely alumina and silica. For the experiments the ore, flux and coke were mixed and milled to 75 µm for 15 minutes for better homogenization. Using a graphite crucible placed into a silica crucible, the crucible was placed in the hot zone of the alumina tube furnace which was programmed at different temperatures. To avoid the reaction between the graphite crucible and the manganese ore. Argon was blown into the furnace from room temperature to 600 °C then switched off to allow carbon only to react with the oxide ore. The furnace was kept for two hours and switched off until the furnace reached 600 °C then argon was blown into the furnace down to room temperature. XRD, XRF and SEM were used for characterization. With the use of alumina as fluxing agent the temperatures used were 1200, 1250 and 1300 °C whereas with silica used as fluxing the temperatures tested were 1200 and 1350 °C. The influence of the A/S (alumina/silica) ratio on the kinetics was assessed.