Metal finishing Q&As since 1989
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Cyanide vs. Non-Cyanide Electroless Nickel Stripper
Intro / synopsis: Proprietary nickel strippers become exhausted and must be dumped whereas cyanide strippers can be re-invigorated and last indefinitely without dumping. On the other hand, cyanide is a dangerous, toxic, heavily regulated material which should be avoided if possible.
Q. We're looking at replacing our legacy cyanide strip for electroless nickel (EN) on steel in favor of an ammonium hydroxide, ethylenediamine, carbamate proprietary one which claims to hold up to 30 grams per liter of nickel. What I'm curious about, does anyone know a comparable number for the conventional cyanide strip we've been using? One of the benefits of the cyanide-based chemistry is that it can be used and re-invigorated over and over before having to discard it. This doesn't seem to be the case for the proprietary one we're considering. Any thoughts or comments appreciated.
Milt Stevenson, Jr.
Syracuse, New York
September 16, 2020
A. Hi Milt. I don't know the answer to that, but while we're waiting I'll offer this general thought -- not for you, who has more experience than I do -- but for the newbie readers who come here for general education ...
Some shops have lots of needs for cyanide: silver plating, copper striking, brass plating, etc. If nickel stripping is one of many uses for cyanide in a shop, carry on with the evaluations. But if stripping is the only use for cyanide in a shop, the superficial economics don't matter, get rid of it :-)
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Milt,
I did a study back in 2001 on some of these proprietary products. I found that they may indeed hold up to about 25 g/L. However, the strip rate becomes drastically reduced at about 10-15 g/L. Beyond 15 g/L you will have customers becoming upset because of the wait and we all know "time is money". I did not do any work then with the cyanide as our shop was not equipped to handle the waste.
- Avon, New York
November 27, 2023
adv.
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