Metal finishing Q&As since 1989

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Removing copper from Silver Cyanide bath

We currently are attempting to remove copper from a silver cyanide plating bath, attempts at dummy plating have not removed the copper, we are still above 10,000 ppm. I was wondering if anybody knew of any other methods to eliminate the amount of copper or what could be wrong with our currently dummy plating process.

Doug Woods
AMI Doduco - Pittsburgh, Pennsylvania, USA
2006

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Hi Doug,
I'm not aware of a precipitation method that would be safe for your AgCn plating solution. I was curious to know your dummy plating procedure. ASF, temp, time? Thanks,

Mark Baker
process engineer - Malone, New York
2006

Since cyanide complexes both metals and the amps/voltage is slightly higher for plating copper than silver, I suspect that you can not economically dummy a silver cyanide bath. If possible, the parameters would be extremely tight. Note, I have a very limited experience with both.

James Watts
- Navarre, Florida
2006

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I have experienced copper contamination in silver cyanide solution and found it near impossible to remove copper via dummying the bath at L.C.D.
Copper ions in solution react with cyanide ions and form a Copper Tricyanide complex which is negatively charged and as such will not be attracted to the cathode. Am I right in guessing your solution is a little bit orange in colour?...this complex in solution gives this characteristic colour as does nickel ions which form nickel tetracyanide complex (overall 2- charge on the complex). My advice ,if economically viable, would be to renew your solution and have the spent solution refined to give you some money back by reclaiming your silver..is this an option?
Hope I have helped some.
Best of luck!

Nigel Gill, BSc MIMF MRSC
- Glasgow, Scotland
2006