The authoritative public forum
  for Metal Finishing since 1989
-----

Non insulated anodes in cyanide zinc tank

Hello, recently I'm running a cyanide zinc plating line in Venezuela, we plate planar steel pieces of 4"x 4" x 0.7 mm average dimensions in a rack of 30 pz each, our baths dimensions are: 1 x 2 x 1 meters, the question is: The anode lead of the rectifier is attached to the steel tank, and the zinc anodes are hanging in a bar welded to the tank... yes they are not insulated! And I don't now why because all the theory say the opposite thing. Please give me some advice about it.

Eduardo González
Plater - Charallave, Venezuela
December 4, 2008

Hi, Eduardo. This was a very common arrangement when I started in this business many years ago, and there is no reason to consider it unworkable, but it is not very common anymore.

Perhaps the biggest downside is that you will generate some quantity of iron cyanide with this arrangement, and removing iron cyanide from your wastewater is not a simple matter because iron cyanide is not amenable to chlorination. If you are suffering from excessive non-amenable cyanide in your wastewater, you may have to go to a plastic lined tank and insulated anodes to resolve it; but if you are not having wastewater problems, there is no reason you can't get satisfactory plating from this arrangement. But when it's time to replace it . . .

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 4, 2008

---

With your system you are using your bath as a part of the anode and you could one day find all your bath on the floor, because you eat specially the weldings off the bath.
Is better to use a plastic bath or you can put specially plastic bags inside the bath

Ricardo Burstein
Bnei Berak, Israel
December 20, 2008