# Wet chemistry method for silver sulfide conversion



## MGH (Oct 31, 2016)

I’ve been building up some silver sulfide as a by-product of stone removal from karat gold jewelry. During the stone removal batches I dissolve the AgCl that builds up with a sodium thiosulfate solution, then pour the thiosulfate solution into a separate beaker where it is converted to silver sulfide (if I have the chemistry correct) by contact with steel wool, with stirring every now and then.

I’ve read in many places throughout the forum that the best/easiest method to convert this silver sulfide is in a gas fired furnace with rebar in the crucible to reduce the silver to elemental metal. Problem is that I do not have a furnace or a cone mold. I’m just working with melting dishes.

I’m wondering if there is a wet chemistry method to make the conversion – something that can be done with beakers and a hotplate. Manuel mentions a couple of options here, but doesn’t go into detail: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=6167

I’m not sure how much silver I have tied up at the moment (maybe 10ozt). It’s not huge, so this is a low priority. If nothing else, I can continue to let it build up, and even transfer the solids to a longer-term bucket if need be.

I do have nitric acid, and I don’t mind AgCl. I’ve done plenty of AgCl conversion using steel and dilute sulfuric acid. Of course I could also try the process that Manuel DOES describe in the above link – still, just asking about a wet chemistry method.

Thanks,
Matt H.


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## Lino1406 (Nov 4, 2016)

Silver chloride can be melted directly to silver with sodium carbonate. http://www.facebook.com/Everymetalchemistry (subject photo)


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## MGH (Nov 7, 2016)

Thanks Lino,

But I wonder if you may have misunderstood what I have. The silver chloride that I do have is the crust that forms on karat gold during direct AR digestion to remove stones from jewelry. I dissolve that AgCl from the karat gold surface using sodium thiosulfate, then the thiosulfate solution goes to a beaker with steel wool to precipitate the silver as silver sulfide.

Are you saying there is a way to convert the silver sulfide back to silver chloride? I would be interested in that.


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## Lino1406 (Nov 8, 2016)

Either AgCl, Ag2S2O3 + NaOH -> Ag2O. Melting -> Ag


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## 4metals (Nov 8, 2016)

> Either AgCl, Ag2S2O3 + NaOH -> Ag2O. Melting -> Ag



Same end result, NaOH but what a difference in the smell! This is not a back yard refining trick, a good hood is advised.


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## MGH (Nov 11, 2016)

Thank you Lino and 4metals. It may be a while until I get back to it, but I'll give it a small scale try some time.


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