Magnesiothermic reduction of beryllium fluoride: Reaction mechanism and kinetic study

Abstract

Beryllium (Be) is mainly produced by magnesiothermic reduction of beryllium fluoride (BeF₂). This research aims to improve the extraction rate of Be by investigating the reaction mechanism and kinetics during the magnesiothermic reduction of BeF₂. It was found that the solid product layer composed of MgF₂ and Be metal produced during the magnesiothermic reduction process is the main reason hindering the further improvement of the reduction rate. Kinetic study on the magnesiothermic reduction of BeF₂ shows that it was controlled by volume diffusion. An apparent activation energy of 66.01 kJ/mol was obtained for the magnesiothermic reduction in the temperature range of 850–950 °C. Aiming to extract Be from BeF₂ with a high efficiency, granular-shaped Mg (particle size 0.2–5 mm) and BeF₂ powder (particle size < 0.83 mm) were used as raw materials for magnesiothermic reduction at 900 °C for 30 min, protected using Ar atmosphere. This was followed by further heating to 1300 °C and holding for 10 min, and the highest extraction rate of Be was achieved at 90.1 wt% with the Be purity of 94.2 wt%.