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  for Metal Finishing since 1989
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Treatment of spent silver baths

i wonder if anybody could inform me on practical experiences with cost effective treatment of spent cyanide containing silver baths with max recycling (electrolytic with subsequent ion exchange)

regards and thanks, gert

gert holm kristensen
Malaysia
1998

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Is it necessary to treat at your facility? The best bet is to send it to a reliable recycler who specializes in this processing.

The use of electrolytic recovery on-site makes sense if you will be following it with chemical destruction (ozone or hypochlorite) then precipitation. No sense making a silver chloride or silver oxide laden sludge when you can cut the weight and volume by over 90% by getting the silver out as metal via electrolysis.

Chemical means are also available for precipitating the silver as silver metal before final cyanide treatment. Unfortunately they will also increase sludge volume since they usually involve zinc or aluminum as reducing agents.

Never run a concentrated bath through ion exchange. It will either break through immediately, or at best, will exhaust the resin much sooner than necessary. Then you have to regenerate the resin, and if doing it on site, you are back where you started with a concentrated cyanide solution.

Bill Vins
microwave & cable assemblies - Mesa (what a place-a), Arizona
1998