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How to implement an agitation pipe in cyanide zinc vat

Hi my name is Allan I have been plating now for about twenty years mostly with acid zinc but recently using cyanide. I would like to know if it's possible to use an agitation pipe to improve plating performance and also use a filter to help clean the solution.

Allan Small
plating shop employee - Southyorks, England
2007

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Hi, Allan, thanks for visiting finishing.com. Certainly you can filter a cyanide zinc bath. However, air agitation is a problem because it will probably lead to excessive generation of carbonates. Mechanical agitation would be better, or you could try an eductor system.

You may notice more "gassing" at the cathode with cyanide zinc than you had with acid zinc. That is evidence of hydrogen being released; some of the electricity you are putting into the process is releasing hydrogen rather than depositing zinc. That is inherent in cyanide plating, so if by "improve plating performance", you mean that you would like the efficiency of the cyanide zinc plating to match the efficiency of the acid zinc plating, you will be disappointed. Good luck,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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2007

Hi, Allan.

May I ask you? what is your consideration to use Cyanide Zinc?
I think many peoples already step out from using Cyanide due to poisonous and expensive waste water treatment cost.

For throwing power or metal distribution I think the latest version of Alkaline Non Cyanide Zinc even better and better current efficiency.

Ted is right, using eductor for mechanical agitation is better and can avoid carbonate build up instead of air agitation.

Best regards,
Tony

Tony L. Chandra
- Jakarta, Indonesia

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First of three simultaneous responses --

Hi Allan,

Go and 'hit' # 9311 and # 7718, this shows how one can increase the efficiency of the 'bubbles' .... but what Tony said about 'eduction' may well make more sense .. I am NOT a plater but just in the plastics' fabricating field.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2007

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Second of three simultaneous responses --

A caveat to what Ted said regarding eductors: When using eductors (or any pumped agitation) It is imperative that air not be entrained in the solution by having the agitation break the surface. Also, be sure that seals on pumps and/or filter pump combinations are not sucking air. Carbonate removal is at best a chore and at worst very expensive.

Gene Packman
process supplier - Great Neck, New York
2007

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Third of three simultaneous responses --

The cyanide zinc bath is very forgiving in ways that the alkaline zinc bath is not - of less than perfect cleaning, mainly. Also, the metal is more easily controlled. Frequently, it is necessary to use a zinc "generator" tank to maintain the metal level in an alkaline zinc tank.
Lastly, to get really top notch appearance, without introducing excessive deposit stress, very careful control of the brightening agents via Hull cell testing is strongly recommended.

I have been hearing that cyanide is on the way out for many years, and perhaps it is. I, personally, regret this. Cyanide sounds scary to many people, and must of course be treated with the utmost respect. But, it is not hard to destroy; it is not an environmentally persistent toxin, as lead or mercury is.

Dave Wichern
Consultant - The Bronx, New York
2007