IMPACT OF Al₂O₃/SiO₂ON THE SLAG SYSTEM IN THE COKE BED ZONE DURING HIGH CARBON FERROMANGANESE PRODUCTION USING BASIC MANGANESE ORES

During High Carbon ferromanganese production, the slag formation plays an important role on the overall process. Though the slag formation starts in the prereduction zone, silica may be reduced depending on the reducing conditions. Stronger reducing conditions lead to some silicon reporting to the metal. The influence of Al2O3/SiO2 ratio on the slag in the reduction zone was investigated. The variation of A/S ratio was obtained by adding silica while alumina was kept unchanged. For better homogenization the ore, flux and coke were mixed and milled to -75 microns for 15 minutes. Bench tests scale were conducted using an alumina tube furnace that was programmed at different temperatures. A graphite crucible placed into a silica crucible; the crucible was placed in the hot zone of the furnace. To create more reducing conditions, carbon monoxide was blown into the furnace at a flow of 0.5L/min. Argon was blown into the furnace from room temperature to 600oC then switched off to allow only carbon to react with the oxide ore. The furnace was kept for two hours at the aimed temperature and switched off until the furnace reached 600 °C then argon was blown into the furnace down to room temperature. XRD, XRF, SEM and EPMA were used for characterization. An alumina tube furnace was used for the experiments. The temperatures used were 1400, 1450 and 1475 °C. The influence of the A/S ratio on phases that formed and the impact on the slag formation in the reduction zone were assessed.