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Converting from Cyanide to Alkaline base on Zinc Plating

adv.
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Q. I'm in an industrial training, So the company want me to make an idea belong how to change the Cyanide that are using in Zinc Plating convert to Alkaline base?

Shah
- Malaysia
2005

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A. If you are presently using a cyanide containing zinc bath you are using an ALKALINE CYANIDE bath. If you want to explore a non-cyanide alkaline bath these are widely used. However, it is generally not feasible to convert [do a sliding conversion] from cyanide to non-cyanide because of the extended time required until the cyanide is completely consumed in the process.

Gene Packman
process supplier - Great Neck, New York

A. Mr. Packman, above, is 100% absolutely correct. I express the same thing this way: If you slide you will create more cyanide bearing sludge to haul away than if you just waste treat the whole CN bath and start from scratch with the Caustic & Zinc. I learned that years ago while involved in changing over a 40,000 gallon zinc solution.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

A. Mr Shah

To switch from cyanide to cyanide free plating..
1) plate with MS anodes , stop adds of cyanide and drop zinc and metal to low values.
Maintain caustic at 70 to 75.
When the zinc and cyanide levels fall to 7 gms per liter or so the bath will not plate well. It will stop working at the low values.
Destroy cyanide using Sodium Hypochlorite.
Use the remaining solution as a soak cleaner off line.
Make up a new bath of alkaline cyanide free zinc using proprietary systems from proven suppliers.

Regards

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016

A. Hi!
You can find some useful information on website pfonline.com ~~in section "articles" in article #049702, or~~ ⇩ Google it with text string "pfonline anatomy of a conversion"

Maybe this can be a little bit helpful.

Best regards!

Dimitrij Us
- Kranj, Slovenija (EU)

Ed. note: Pfonline is re-arranged, but the googling works :-)

Indeed it is helpful, Dimitrij. It also suggests replacing cyanide with non-cyanide outright, not wih a sliding conversion.

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

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