Reaction Behavior of Stratified SiO(2) Granules during Electrochemical Reduction in Molten CaCl(2)

Abstract

The electrochemical reduction behavior of stratified SiO(2) granules in molten CaCl(2) at 1123 K (850 °C) was investigated to develop a new process for producing solar-grade silicon. The cross sections of the electrolyzed electrode prepared from a graphite crucible filled with SiO(2) granules were observed and analyzed. The visual and SEM observations indicate that the overall reduction proceeds via two different routes. In one route, the reduction proceeds along the granule surfaces from the SiO(2) near the conductor to the distant SiO(2). In the other route, the reduction proceeds from the granule surface to the core of each granule. The reduction along the granule surfaces is faster than that from the surface to the core. Fine SiO(2) granules are expected to be favorable for a high reduction rate.