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Material selection for corrosion prevention in cyanide solutions

I wish to electrowin silver from silver cyanide at pH 14+. What anode material can you suggest. 316SS corrodes rapidly.

Steve Lloyd
- Ashmore, QLD, Australia
2001

The SS sheet or mesh anodes of 316 alloy commonly used for electrowinning, should not corrode rapidly, in my experience, unless you are using excessive hypochlorite, or similar chlorine source chemicals, to destroy the cyanide. SS will eventually pit in any chlorinated solution, even diluted like seawater. The rate is time, temperature and concentration directly dependent, and any sludge that may stick to the SS, could cause concentration cells to form under it. Also, look closely at how you remove the electrowon material off the SS. Could it be you are damaging the surface, making it susceptible to corrosion? Good Luck.

W. Carl Erickson
- Rome, New York
2001