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47081
Precipitating nickel from enickel
dragout
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A colleague of mine asked me to figure out way to remove Ni from
Enickel bath dragout. I recommended 2,4,6- Trimercaptotriazine
(TMT--Degrussa)as a method because of very high caustic demand for
dropping nickel. That option was also considered too expensive. Email
from colleague today says ammonia is the cause for high caustic
demand. How about sodium sulfide as a Ni precipitant?
Russell Pickett
environmental consultant - Butler, Tennessee, USA
First of two simultaneous responses -- +++++++
Firstly methods should be employed to reduce drag out and recover
drag out for reuse in the operating tank. It has proven practical, in
my past experience, to concentrate the drag out and electrowin much
of the nickel.
Gene Packman
- Great Neck, NY
Second of two simultaneous responses -- +++++++
Sodium sulfide works great. However, people tend to shy away from
it because of the possiblity of generating H2S - it's released on
acidification of sulfide bearing liquids.
A safer solution that's often used is ammonium dimethyl dithio
carbamate. It's sold by
Luster-On Corporation, who
has a presence on the site here.
You speak of "high caustic demand" - you are going to have to raise
the pH to at least 8 to use any precipitant that I'm familiar with,
and I've been treating nickel wastes for a long time.
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Dave Wichern
- The Bronx, New York
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