The silicothermic reduction of magnesium in flowing argon and numerical simulation of novel technology

摘要

The silicothermic reduction of magnesium was investigated by the non-isothermal thermoanalysis in flowing argon,while the traditional investigations of silicothermic process for magnesium reduction were carried out under vacuum conditions.Firstly,the thermal gravimetric(TG)and derivative thermogravimetric(DTG)characteristic of briquettes prepared with calcined dolomite,ferrosilicon and fluorite were characterized by the thermogravimetric analyzer(TGA)at different heating rates.The intrinsic chemical kinetic mechanism was identified as a formal chemical reaction with the Nth order type which showed apparent activation energy E and reaction order n were 290.168 kJ mol^(-1) and 1.076,respectively.Then,a novel technique of magnesium production without vacuum was put forward and a three-dimensional unsteady numerical model incorporating the chemical reaction,radiation,heat conduction and heat convection was established and simulated,which was verified by Pidgeon process and novel tech no logy.rIhe nu merical results showed that the cycle time of the novel technique could be reduced when the argon temperature was higher than 1343 K and the argon entrance velocity was over 0.05 m s^(-1).And the effect of the argon temperature on reduction degree was much larger than that of entrance velocity.