PROCESS FOR PRODUCING HIGHLY PURE SILICON

摘要

Provided is a process for producing highly pure silicon. The reaction products are completely separated and recovered to reuse in the process so as to achieve low cost large-scale production of highly pure silicon. Specifically, use is made of vessel 1 with temperature maintained at 910 to 1300?, vessel 2 with temperature maintained at 300 to 400? and vessel 3 with temperature maintained below 0?. The outlet side of vessel 3 is communicated with ambient atmospheric gases through exhaust gas treatment devices. Vessels 1, 2 and 3 are connected in series, silicon tetrachloride gas, zinc vapour and inert gases with purity of 6N are feed from the inlet of vessel 1, and excess stoichiometric ratio of silicon tetrachloride to zinc is kept at the pressure of 1000 to 1200 hPa, thereby achieving a zinc-free state in the system. Granular silicon is obtained in vessel 1, molten byproducts zinc chloride and particulate silicon are obtained in vessel 2, and the residual silicon tetrachloride is recovered in the liquid state in vessel 3. The byproducts zinc chloride in vessel 2 is directed to aqueous solution electrolysis after particulate silicon is recovered, and zinc is recovered to reuse.