HF MEASUREMENTS INSIDE AN ALUMINIUM ELECTROLYSIS CELL

摘要

HF emissions to the working atmosphere may still be a problemrnfor the aluminium industry. The objective in the present work wasrnto study how the HF evolution is distributed between feeder holes,rnother openings in the crust, gases diffusing through the crust,rnfumes from the secondary alumina residing on top of the crust etc.rnA movable “gas sniffer” connected to a Tunable Diode Laser wasrnused to measure the HF concentrations at the above mentionedrnlocations. The stationary HF level in an open flaming feeder holernwas approximately 9000 ppm, when measured a few cm above thernbath surface. In comparison, when the probe was positioned 5-10rncm above a crust area with good integrity, the HF concentrationrnwas in the range 5-10 ppm. The results support the notion thatrnmost of the HF evolves from open feeder holes and the tappingrnhole.