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Cadmium plating waste products

Q. I am currently handling the environmental aspect of waste produced at one of our clients following Cadmium Plating in the aviation industry. I have very limited knowledge on this process and I would appreciate if anyone can shed some light on what to expect as a byproduct of this process. All I know is that they end up with blackish liquid which I have not dared to smell or touch but the viscosity looks very similar to that of water.

Thank you for any support you can provide!

Regards
Dan

Daniel Borg
- Qormi, Malta
February 15, 2012

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Is this cyanide cadmium plating? (most is, in my experience.)

I would chlorinate at pH 10.5 to complete cyanide destruction, stir for 30 - 60 minutes, then neutralize excess chlorine with sodium metabisulfite. Then, I'd add a touch of Ca(OH)2 slurry to bring the pH to 11 or so, then add flocculant to settle solids. This ought to bring the Cd down to less than 0.5 ppm.

Lower residuals can be gotten by adding a sulfur based precipitant, like Na2S, or DTC, prior to the pH adjustment.

Dave Wichern
Consultant - The Bronx, New York
February 15, 2012