Sulfur Balance Between Dry Scrubber and Electrolysis Cell in Order to Understand Effects of Pot Gas Recirculation

To capture CO₂ efficiently from aluminum smelters, it is beneficial to reduce the overall amount of gas to be treated. This can be done by off gas recirculation, where off gas is conditioned and reintroduced to the cell. The mass balance of sulfur across a dry scrubber is of essential importance to plan for. In preparation for possible modifications of the Pot Integrated Abart (PIA) concept to recirculate off gas for CO₂ up-concentration insight in the sulfur balance between the raw gas, gas emerging from the scrubber and sulfur adsorbed on the secondary alumina was needed. A measurement campaign using Fourier Transform Infrared spectroscopy (FTIR) on both raw gas and scrubbed gas simultaneously along with SO3 sampling, and samples of secondary alumina from the PIA were designed. The equilibrium between SO₂ and SO3 is of high importance as accumulation of SO3 in the raw gas loop can lead to condensation of sulfuric acid.