Upgrade Silicon Powder Prepared by SHS with Acid Leaching Treatment

Abstract

Upgrade silicon powder have been prepared by a two-stage technique consisting of a self-propagating high-temperature synthesis (SHS) process in a SiO2+Mg system in an inert atmosphere and the hydrometallurgical treatment of the combustion product. It was found from DTA curve that the initial starting temperature(Tin) of the reaction was 615°C. The adiabatic temperature (Tad) of system was calculated under the different molar ratios of Mg/SiO2 and the results showed the reaction would happen and be kept by the self-propagating way only when the excess coefficient(x) of Mg was more than 0.9. The value of Tad would increase with the increasing of x. XRD Pattern indicated MgO2 and element Si were main phases in combustion products except a little matter MgSi2O4. The purity of the combustion-synthesized Si samples was greater than 99.98% after the acid leaching treatment, and the experimental yield of the powder was approximately 78%.