Ammonium thiosulfate is used in
photographic fixer. It is a so-called rapid fixer, acting more quickly than
sodium thiosulfate fixers. Fixation involves these chemical reactions (illustrated for
silver bromide): : : Also exploiting the stability of
thiosulfate coordination complexes, ammonium thiosulfate is also used for
leaching of
gold and
silver. It works with presence of
copper as a
catalyst. This process is a nontoxic alternative
gold cyanidation. The advantage to ammonium thiosulfate is that the pyrolysis of its silver complexes leaves a residue solely of silver sulfide, in contrast to complexes derived from sodium thiosulfate. As suggested by some research studies, it can also be used as an additive to
coal-
waste mixtures to reduce formation of
dioxins and
furans during combustion. ==Safety==