Upgrade silicon powder prepared by SHS with acid leaching treatment

摘要

Upgrade silicon powder have been prepared by a two-stage technique consisting of a self-propagating high-temperature synthesis (SHS) process in a SiO_2+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(T_(in)) of the reaction was 615°C. The adiabatic temperature (T_(ad)) of system was calculated under the different molar ratios of Mg/SiO_2 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 T_(ad) would increase with the increasing of x. XRD Pattern indicated MgO_2 and element Si were main phases in combustion products except a little matter MgSi_2O_4. 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%.