These are some of the substances to be found in used potlinings
from aluminium reduction cells. They were at one time disposed of
by ground burial. This was not a good idea since as well as
various fluorides and carbides, they also contain substantial
amounts of cyanide
Under a US Bureau of Mines, I led an investigation into finding
the best way of treating these materials, which was the subject
of one of the cover mentioned stories in the Journal of Metals.
My recommended approach was to pressure cook the old potlining in
hot water, and then recover the carbon to be recycled into new
potlinings.There would still be some residue,but it would be safe
to dump. I believe ALCOA now does something along these lines .
