Behavior of sodium sulfate in cryolite-alumina melts and formation of sulfurous gases

The study of the behavior of sulfur compounds in the Hall-Heroult process is of particular interest not only due to the emitted harmful gases, but also its potential effect on the process of aluminum production. The source of sulfurous gases from aluminum smelters is mainly the carbon anodes, which contain sulfur in organic sulfur ring structures. Sulfur is also introduced in small amounts by the added alumina, mostly in the form of sulfates. The sodium sulfate reactions and the gaseous products emitted from electrolysis cell were studied at different conditions and analyzed by using ICP (Inductive Coupled Plasma) spectroscopy, XRF (X-Ray Florescence) and MS (Mass Spectroscopy). The sulfurous gases that were observed include: SO2, COS, CS2 and H2S.