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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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What to do with scrap cadmium plated parts?
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Q. I am looking for the right (legal, ethical, environmentally logical, etc.) to scrap out old Cadmium (usually with hexavalent chromium top coat) plated alloy steel parts returned from service.
We are trying to switch to Zi-Ni with trivalent chromium top coat, but what do we do with the scrap "coated steel parts"?
Do we note it as Cad and chromium contaminated waste and send it to the metal recycler or must we strip before scrapping?
In aero we like to mutilate old part before scrap.. that is tricky when cad with chromate coating too.
Advice or direction to hard fast rules / laws to follow are most welcome.
Aerospace Design Engineer - Erie Pennsylvania
December 21, 2021
A. Hi Kirk,
It sounds like you have (or you will have) a continuous flow of Cd plated scrap parts. Maybe it makes sense to set-up a small bath for Cadmium stripping (Ammonium Nitrate solution ~120 g/L, room temp.)? The stripping process is relatively fast, the bath will survive for many months. At the end, you will have to dispose the liquid as Cd contaminated waste (once), but all your steel parts will be Cd free for marking and scrapping.
Good luck,
- Winnipeg, Canada
December 30, 2021
A. Hi. I think Leon has a good idea. You can search the site for many threads about stripping cadmium plating. I think the stripping solution is not waste until it's waste. But if you start drawing some off so you can strengthen it, I think what you draw off is waste and you need to mark and pay attention to the start date of waste accumulation.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 2022
January 3, 2022
Leo and Ted, Thanks!
I have had our local plater strip some old fielded bolts for testing just to be safe when handling the old bolts, it worked well and one would assume the shop followed the rules on waste disposal as they also still do Cadmium plating.
Q. What I really need is someone to point me to the rule / law / guidelines that say "You cannot just throw out Cadmium plated (with Hexavalent Chromium) plated hardware when you know it exists."
Does my scrap metal handler have some sort of process to sort? I doubt it. Does the scrap metal process safely handle and melt down Cadmium and Hexavalent Chromium plated metals? Possibly, but I just do not know.
Aerospace Design Engineer - Erie Pennsylvania
A. Hi again, Kirk. I am not at all sure that there are any regulations on the disposal of cadmium metal or cadmium plated metal. You might talk to people involved in recovery of cadmium like Inmetco who reportedly recycle nickel-cadmium batteries.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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