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Letter 1041
Treatment of spent silver
baths
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i wonder if anybody could inform me on practical experiences with
costeffective treatment of spent cyanide containing silver baths with
max recycling (electrolytic with subsequent ion exchange)
regards and thanks, gert
gert holm kristensen
Malaysia
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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 immediatly, 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.
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Bill Vins
microwave & cable assemblies
Mesa (what a place-a),
Arizona
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