Prebaked anodes used in electrolysis cells for the production of aluminium have to be replaced periodically. Once used anodes (butts) are removed from the cells, they are usually placed on anode trays for transportation and cooling, a process during which Hydrogen Fluoride (HF) is generated in large quantities. HF gas is particularly toxic for the environment and human beings as well, hence the need to reduce HF emissions.
In collaboration with Alcoa Canada, STAS has developed the CAT / Covered Anode Tray, a specifically designed container that permits to reduce contact between the anode butts and the ambient air by confining the anode butts in an enclosed container shortly after their removal from the cells. Such a system significantly reduces HF emissions when the anode butts are cooled down (50% reduction).
The panels of the closed container are automatically activated by the movement of the anodes when they are inserted or removed. A patented mechanism used to seal the gap around the anode rod ensures optimum confinement while minimising the maintenance costs. The geometry of the containers can be easily adapted for use with most of the anode trays.
A Simple and Efficient Way to Reduce HF Emissions from Anode Butts.”