This project examined calcination of Tasmanian (Australia) ironstone ore in different gas atmospheres and carbothermal reduction of the ore at 1400-1600 oC in CO atmosphere. The project also studied the rate of quartz dissolution in silicomanganese slag and reduction of silica from the manganese ore-quartz mixtures into SiMn alloy. The phases formed during the reduction reactions were characterized by XRD and SEM and then compared with the calculated equilibrium phases using CSIRO’s Multiphase Equilibrium model and FACTSage. The project’s aims included assessing the feasibility of using Tasmanian ironstone ore, which is rich in iron and silicon, in the production of silicomanganese and further development of understanding of processes of SiMn production.Ironstone ore was provided in the form of a crushed and lumpy ore. Crushed ore contained higher Fe2O3 concentration and lower SiO2 content compared to the lumpy ore. The main phases in the ore were hematite and quartz. Partial reduction of iron oxides and formation of fayalite were observed upon reduction of ironstone in CO atmosphere. Ore softening and partial melting at 1100 -1150ºC had a significant negative effect on the iron oxide reduction. Phases identified in the carbothermal reduction of ironstone ores at 1400°C, included quartz, cristobalite and metallic iron. Reduction of iron oxides at 1400°C was close to completion. Silica was also reduced forming Fe-Si alloys. The extents of silica reduction in the crushed and lumpy ores at 1600°C were 82 and 81% respectively. Ironstone ore demonstrated appropriate properties and reduction behaviour for utilisation in SiMn production.Low rate of quartz dissolution into the SiMn slag can contribute to the reaction rate control in the process of reduction of silica in production of silicomanganese. Thus the dissolution rate and solubility of quartz in silicomanganese slag were studied in the temperature range 1400 -1550 °C under argon. The dissolution rate of quartz was measured using a rotating rod technique; quartz solubility was examined using static experiments. The dissolution rate of quartz was controlled by mass transfer of silica in the slag. Silica diffusion coefficients in silicomanganese slag varied from 0.9x10-7 to 1.3x10-6 cm2/s, depending on temperature and slag composition.
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