Metal finishing Q&As since 1989

-----

Air emissions from cadmium electroplating

I am trying to determine the emissions of Cadmium and Sodium Cyanide into the air that result from cadmium electroplating, when a cyanide-based solution is used.

Can anyone lead me in the right direction?

Francis Craner
New York
1999

---

Francis, I am very perplexed as to just why you even want this information! I am not a plater ... anyhow, doesn't 'The Book' infer (& I haven't bothered to look at it just now) that cyanide plating solutions need zero or very little exhaust as they are, the fumes are, not very toxic? My past interest re plating plants was the exhausting of nauseous fumes and scrubbing them, IF NECESSARY. I cannot recall running across a cyanide bath that needed scrubbing as it was probably most unnecessary and a complete waste of good $. Please enlighten me. Try the local EPA. They set the standards. ...curiousity killed the cat, etc. Yours truly, Freeman Newton, .

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
1999

---

It is true that Cadmium cyanide has historically rated a D-4 classification in the ANSI, OSHA, and ASGIH guidelines, meaning that the hazard rate is as low as it goes and the evolution rate is nil as well.

Perhaps the best study ever done was NIOSH pub. no. 85-102, "Control Technology Assesssment: Metal Plating and Cleaning Operations" by Sheehy, Mortimer, Jones, and Spottswood. That study showed cadmium levels in area samples to be below the detection limit in all four facilities tested. Both cadmium and cyanide operator exposures were below the detection limit in most cases, and less than 1/50 the PEL and less than 1/10 the OSHA recommended standard in the worst case. (The PEL and OSHA standard may have been revised since 1985, I haven't looked it up). The bottom line, quoting from the report, is: "exposures to cadmium and particulate cyanide from cadmium cyanide plating tanks are very low. This is true whether the tanks are ventilated or not."

However, cyanide solutions are extremely hazardous in the presence of acids, and some people of experience feel that they therefore should be ventilated. Count me in that group! As a 30-year-old startup engineer for a plating equipment company, I was alone, and ignorantly moving the plating barrels around to position them for our programmed hoist, when I darn near killed myself depositing a poorly rinsed acid barrel into the cyanide tank. Just as belt guards and chain guards and other safety devices are required because people sometimes do stupid things, when you have a large vat full of a solution that can rapidly evolve a highly toxic, instantaneously acting poison, it ought to be ventilated--not for day-to-day exposure, but as a reasonable safeguard against catastrophe.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey