Electrowinning of Silicon using SiO2 – Overview and Industrial Perspectives

Decarbonization of the silicon production process can be done by electrowinning from SiO2 at high temperatures using molten salts or oxides producing O₂ as the anode product. Thermodynamics combined with knowledge of state-of-the-art electrowinning processes can provide an understanding of the possibilities and limitations of the approach, to best compare with today’s submerged arc furnace (SAF) process. Carbon, if used in carbothermic reduction or as a consumable anode in an electrowinning process, provides energy that is not available when the carbon is eliminated from the process. The result is that an optimized electrowinning process is likely going to require more energy than by SAF, and renewable energy must be used to eliminate the CO₂ from the process. This work further details the knowledge needs related to dissolution behaviour of the SiO2, electrode materials, cell design and upscaling for both solid and liquid Si production.