CADMIUM
AND CYANIDE METAL SALTS
There are many
ways to treat cadmium but the main emphasis has been to convert
it to a cation and precipitate it as a hydroxide sludge. It can
be electrowinned but the cadmium metal may (it is not uncommon)
auto ignite when dry and exposed to oxygen (not good). Electrowinned
Cadmium cathodes should be kept under water.
Zinc, Copper, Silver
and Gold are also plated from cyanide baths. Gold is recovered
from ores as a cyanide. This literature also applies to these
metal complexes. Electrowinning works well for all of these metal
cyanide complexes.
Cadmium is plated
from cyanide solutions so often cyanide destruction must be performed
before the cadmium can be removed from solution. Cyanide is destroyed
by oxidizing it with an oxidizer such a bleach at a high pH (10.5)
to convert it to cyanate. Full destruction is obtained by lowering
the pH to 8.5 later and adding more oxidizer to destroy the cyanate.
Cyanide can also be destroyed in an electrowinning cell with simple
salt (NaCl) added.
The following links
will take you to sites that review the basic treatment technologies.
Each source (your water) should be analyzed and specific treatments
tested before you invest in a system.
Cadmium
and Cyanide Literature on the Web
Click on the highlighted
web address to go to the web page listed. Hit back on your browser
(right click mouse) to get back here if you want more.
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