Abstract
Characterization of the off-gases from a 500 A inert electrode aluminum electrolysis cell operating at a temperature of ca. 800 °C has been conducted using characterization units comprising gas chromatography, tuneable diode laser spectroscopy, and Fourier-transform infrared spectroscopy. The off-gases detected from the inert electrode aluminum electrolysis cell have been compared to the off-gases released from the traditional Hall-Héroult aluminum electrolysis cell. All the measurements from the inert electrode cell confirmed oxygen as the main process gas during the electrolysis process. Hydrogen fluoride, HF, which is assumed to result from reactions between moisture in the alumina raw material or the surrounding air and the fluoride melt, was also observed together with gases assumed to come from air introduced, such as nitrogen and CO(2). There were no indications that these gases came from the production process. A very small amount of SiF(4) was also detected.