Patent ID: 7972584

Claim:
A magnesiothermic method of producing solid silicon comprising: (a) reacting solid silica and magnesium gas at a temperature within a range from about 400° C. to about 1000° C. to produce solid silicon and solid magnesium oxide by the reaction SiO 2 (s)+2Mg(g)→Si(s)+2MgO(s), the solid silicon having a purity within a range from 98.0 to 99.9999%; (b) reacting the solid silicon with magnesium gas to produce solid magnesium silicide by the reaction Si(s)+2Mg(g)→Mg 2 Si(s); (c) contacting the solid magnesium silicide with at least one of hydrogen chloride gas and hydrochloric acid to produce silane gas; (d) thermally decomposing the silane gas at a temperature above 350° C. to produce solid silicon and hydrogen gas by the reaction SiH 4 (g)→Si(s)+2H 2 (g), the solid silicon having a purity of at least 99.9999%; (e) separating the solid silicon and hydrogen gas into two processing streams; and (f) recycling the hydrogen gas for reaction with chlorine gas to produce hydrogen chloride gas.