# SILVER + nitric acid and a newbies mistake.



## AmatureSmelter (Apr 29, 2017)

Hi all I am new to refining from scrap silver. What I have been doing is just melting the silver down into bars from the scrap I have gotten. I then skim off the slag before I poor it. However I have been reading about nitric acid refining methods.... that being said I made the mistake of trying it when I was aggravated at the impurities still in my silver. I used all of my testing solution, put it in a glass container and just tossed some of my silver bars in and a couple of other pieces of scrap. Not checking them first, turns out there was some silver plated items with a copper base. And I did not dilute the solution like i should have.... so this is the result.... see photo. Is it all silver or is it a mix of crap?


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## FrugalRefiner (Apr 29, 2017)

Welcome to the forum!


AmatureSmelter said:


> I used all of my testing solution, put it in a glass container and just tossed some of my silver bars in and a couple of other pieces of scrap. Not checking them first, turns out there was some silver plated items with a copper base. And I did not dilute the solution like i should have.... so this is the result.... see photo. Is it all silver or is it a mix of crap?


That's a hard question to answer. You say you used all of your testing solution. What kind of testing solution?

You tossed in some silver bars and other pieces of scrap, and you now feel some were silver plated with a copper base. What led you to that conclusion? Did you remove something and find it was stamped silver plate, or are you basing it on the color of the solution?

Your picture shows a good volume of solution above some precipitate. How did you get there? Did all your material dissolve and then you cemented with copper, or is this just the result of having put your material into this "testing solution"?

The more details you provide, the better answers we can give you.

Dave


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## AmatureSmelter (Apr 29, 2017)

The testing solution was a mix of nitric, muratic and some potassium. The mix was left to sit for an hour when i tried to filter it that is when a piece of the (SILVER plate neclace ) dropped out. The neclace was partially dissolved.

I feel that the copper in the acid solution started to acement out the silver while it was being dissolved. So essentially I am thinking that the sludg in the container is still contaminated by the other base metals that i think are in the material I used. 

The photo is some of what I placed In the acid. What I had melted down all said either 925 or 800 or 900 silver or sterling only the neclace did not have any markings i should have left that one out


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## FrugalRefiner (Apr 29, 2017)

AmatureSmelter said:


> The testing solution was a mix of nitric, muratic and some potassium.


Well, that's the first problem. Nitric dissolves silver. Muriatic does not. When you put silver in a combination of the two, you create insoluble silver chloride. That's probably the bulk of your precipitate.

The silver plated necklace wasn't the problem, the HCl was. Now you can search for ways to convert the silver chloride to metallic silver. There are several, each with their advantages and disadvantages. If I tried to describe them all here, I'd have to write a small book, so I'll just say that the search function and patience are your friends.

Dave


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## geedigity (Apr 29, 2017)

Silver metal and 50% nitric acid solution make a water soluble compound called silver nitrate. If there is also copper metal mixed in with the silver metal, then an additional product of the above reaction will include a soluble copper nitrate (maybe the bluish color in your solution). 

Not sure why you would add hydrochloric acid (muratic) to that mixture. If you add a chloride ion to the above silver/copper nitrate solution, insoluble silver chloride forms. 

So it sounds like you were testing various silver items and melts and you got frustrated and threw all of your testing solution (I assume it was Schwerter's) and melted silver into a container? I would guess there is not much silver in solution.

Note that a typical silver testing solution would only contain nitric acid, water and potassium dichromate.


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## Topher_osAUrus (Apr 29, 2017)

AmatureSmelter said:


> The testing solution was a mix of nitric, muratic and some potassium.



What kind of potassium? Dichromate I hope.. Haven't read any good refining procedures that use bananas, but I'm always willing to learn. :wink: 

You mentioned that some may have been plated? What did the bar look like from that melt? Did it look silver? Brass toned? Firescaled badly? It may have been german silver, nickel silver, whatever silver (it has dozens of names) and it contains zero silver. But, from the looks of your solution the majority is silver chloride, as these good gentlemen above have already pointed out.

Siphon off the solution atop the insoluble chloride. Then rinse the silver chloride well, very well, until the rinses are clear.
Cover the AgCl with water, tap will do fine. Add a handful of nails in there, then start to stir, slowly adding sulfuric acid. Once it begins to bubble stop adding the sulfuric. Keep stirring. And stirring, and stir some more. When you think its done, keep stirring for a bit longer. 

Silver chloride will begin to shift colors from white to a dark grey, this will now be your elemental silver. Remove the nails, and rinse them off. Allow it to settle. Decant, rinse until clear again. Dry and melt, then stop and study. You will be very glad you did! (trust me, an internet rando)

No sulfuric? Well (Dave is a busy man, but I am a bored one, so I will write you a chapter or two of the book he mentioned  )

Instead of adding nails to the water covered AgCl, add a bit of aluminum scrap (or zinc, if that suits you better) and then add some HCl until it begins to effervesce. Again, stir like a mad man. The conversion is a contact one, so the silver chloride MUST touch the sacrificial metal before it can become silver metal again.

The only downside to this method, with aluminum or zinc, is the solution looks as if it has silver suspended that refuses to settle. It's not, just be sure to give it ample time for the silver to settle(hour, two hours maybe), then procede to siphon off the baren solution and start the wash process.

If either of those does not suit your style, there are PLENTY more methods to convert the silver chloride. All of which have been mentioned on the forum at one time or another. An advanced search for "silver chloride conversion" will probably bring up a billion results.


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## g_axelsson (Apr 30, 2017)

A few links here...
http://goldrefiningwiki.com/mediawiki/index.php/Silver_chloride

Göran


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## upcyclist (May 1, 2017)

The last picture shows a darker precipitate. Assuming it's not just due to lighting, darkening in sunlight is a very good sign you're looking at silver chloride. Try stirring it--if it turns white again (because only the outer layers darkened), that's a definite sign of photo sensitivity.


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