SILICOTHERMIC REDUCTION OF THANHHOA DOLOMITE: THERMODYNAMIC AND EXPERIMENTAL

Thermodynamic and experimental studies was carried out on the process of Thanhhoa dolomite reduction to produce magnesium. Thermodynamically studied on the effect of pressure and temperature on reduction was carried out together with verification experiment. Results show that at appropriate temperature and vacuum pressure, Thanhhoa dolomite can be reduced using ferrosilicon as the reductant. The higher level of vacuum, the lower temperature required for reduction. Thermodynamic calculation pointed out that at a vacuum pressure of 600 Pa, the reduction temperature could be as low as 1140 °C. Experiment results indicated that at although reduction could be done at 1150 °C, the process efficiency was low, generally below 20%. Process efficiency enhanced as temperature increase and reaches the highest value of 85,8% at 1250 °C (25 wt.% ferrosilicon). The amount of ferrosilicon used also has influenced the process efficiency. After three hours of reduction, the obtained magnesium was very high in purity, 99.3%.

Desiliconization of leucoxene concentrate through the vacuum silicothermic reduction

A new approach to the processing of leucoxene concentrate through the vacuum silicothermic reduction of titanium and silicon oxides using technical silicon as a reducing agent is presented. It has been shown that the reactions occurring during the high-temperature process are accompanied by the formation of SiO gas resulting in desiliconization of the leucoxene concentrate. The highest desiliconization degree of 82 % was achieved when the content of silicon in the reactant mixture was 29 wt. %.