HF emissions to the working atmosphere may still be a problemfor the aluminium industry. The objective in the present work wasto study how the HF evolution is distributed between feeder holes,other openings in the crust, gases diffusing through the crust,fumes from the secondary alumina residing on top of the crust etc.A movable “gas sniffer” connected to a Tunable Diode Laser wasused to measure the HF concentrations at the above mentionedlocations. The stationary HF level in an open flaming feeder holewas approximately 9000 ppm, when measured a few cm above thebath surface. In comparison, when the probe was positioned 5-10cm above a crust area with good integrity, the HF concentrationwas in the range 5-10 ppm. The results support the notion thatmost of the HF evolves from open feeder holes and the tappinghole.
展开▼
