Experimental and numerical investigation of silicothermic reduction process with detailed chemical kinetics and thermal radiation

This paper presents an experimental study on the intrinsic chemical dynamics mechanism of the silicothermic reduction process and a single uniform chemical reaction model which is in accord with Arrhenius' equation under the silicothermic reduction conditions was obtained. The equation of the uniform chemical reaction model can be represented by 1-(1-α)1/3=k0exp(-E/RT)τ in the temperature range 1273-1473 K (1000-1200 °C) and the apparent activation energy is a function of reaction time. Then, a three-dimensional unsteady numerical approach incorporating the chemical reaction, radiation and heat conduction models was first developed and verified by industrial production data of the magnesium production enterprises. The most appropriate radiation model was proposed and the simulations of the impact of radiation heat transfer on the magnesium reduction extent and temperature distributions were carried out utilizing this model. The analysis showed that the radiation heat transfer is an important factor in the heat transfer process in the retort. For the intensity of the radiation varies dramatically with temperature, the radiation model must not be ignored or simplified to be a heat conduction mode during the numerical calculation for the purpose of increasing the calculation accuracy. It is also concluded from the numerical results that the heat transfer efficiency is low in the initial stage, so improving the heat conduction rate could increase the magnesium production capacity, especially in the initial phase of the reduction process.