Metal finishing Q&As since 1989

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Better reclamation of gold from stagnant gold rinses

2003

I've had the same reclaim system on my gold stagnant rinses for years. The basic anode/cathode unit with no bells and whistles. I back this up with a anion resin tank system. I have recently heard of some improvements over the years and was wondering what might really work for better reclaim. Please comment on the following suggested improvements:

1) Hot water stagnant rinse (heater) for better gold reclaim and reducing algae built up.
2) Filter the water in the stagnant rinse continuously.
3) Add flow disperser or air sparger for improved rinse water circulation in cell. Question...doesn't this increase the algae?
4)Daily backflushing of the anion resin tanks.
5 Sand filter instead of pleated cartridge filters in front of resin tanks. I fight algae in my stagnant rinse tank but draining twice a week has helped this.

All comments and other suggestions are welcome!

Donald L Putman
printed circuit boards gold plating - Johnson City, New York

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It is difficult to say for sure in your case, but, in general, I don't recommend both electrolytic and IX recovery on the same tank. The reason for this is that the IX will remove Gold down to < 0.1 mg/L, and remove most of it before the electrolytic cell can recover it. I would recommend increasing the agitation (with a pump or mixer) in the electrolytic cell, and moving the IX to the subsequent flowing rinse. This should recover most of the gold electrolytically, and in this tandem configuration, remove > 99.9% of all of the gold (and cyanide, assuming that it is an acid gold plating bath).

Lyle Kirman
consultant - Cleveland Heights, Ohio
2003