Dry adsorption
All pots are closed, and fumes are sucked into a dry adsorption plant where fluorine and dust are removed. Within the dry adsorption plants, the fumes are exposed to alumina, whereupon the fluorine bonds to the alumina particles. The previously pure alumina has now become secondary alumina. When the secondary alumina is pumped to the pots it contains fluorine, which is reused in production. In this way, over 99% of fluorine carried to the dry adsorption plants from the pots are recovered. Filters are used to remove the dust from the fumes.