Hydrolysis of Carbonyl Sulfide (COS) on Smelting Grade Alumina

Carbonyl sulfide (COS) is present in aluminum smelter off-gas at low ppm concentrations. The primary source of COS is the 2–3 wt% sulfur contained in carbon-based anodes. COS is directly evolved from anode oxidation during aluminum electrolysis. Upon evolution, COS is further oxidized to SO2, while a minor fraction of evolved sulfur is emitted in the form of COS. Very little, if any, of the evolved COS is captured by the dry scrubbing systems.