# Weird Reaction While Dropping Silver



## metatp (Apr 24, 2010)

Ok. Has anyone ever seen this. Now that I have some nitric acid, I've been doing a lot of evaluation of the silver I have, especially the items with low silver content. These were "L" shaped contacts that tested positive for silver. I dissolve a small sample and recovered about 50% silver, but the silver was very dark and I had to wash with HCL to get to the grey color I expected. The solution that was filtered out was a dark purple or bluish color, it took a lot of water to get the solution almost clear. 

I decided to try a bigger batch, and also wanted to complete these for the required more work to recover the silver, and I will probably refine the cement again to clean it up a bit. The picture below is the result that were very weird.

After dissolving about 50% of the metal in nitric acid 50/50, the solution was almost lime green with a mustard orange slug. After filtering the rest of the contacts and the slug, the solution was a light greenish color. When I placed copper in the solution to drop the silver, the cement we a very dark grey (which is what I expected) and the solution was dark black or blue. There was a lot of sizzling and when I left the solution to do its thing, it grow into the picture attached. Has anyone ever seen this before?

Here is another strange thing. When I stirred the frothy crystals, it all when back into solution. I have not idea what would cause this reaction. Very interesting, but too much work.

Tom


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## Platinum (Apr 25, 2010)

Was it copper powder or a bar. Chlorides :?:


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## metatp (Apr 25, 2010)

It was a copper pipe. It looks like copper chloride, but I don't know where the Chloride would come from. I would thing that if chlorides were present, silver chloride would have been created.


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## qst42know (Apr 25, 2010)

Your contacts may have had a nickel content. Do a google search for images of nickel nitrate. The color is almost identical. You can test with DMG to confirm.


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## metatp (Apr 25, 2010)

qst42know said:


> Your contacts may have had a nickel content. Do a google search for images of nickel nitrate. The color is almost identical. You can test with DMG to confirm.


Unfortunately, I do not have any DMG yet. The acid test did not show much or any nickel. I have had nickel in my nitrate solution before with no issue like this. Why would it form when adding copper metal. This is very confusing, but interesting.


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## qst42know (Apr 25, 2010)

Nickel was only a guess you would need to test to confirm. Contacts can be a complex alloy of very many different metals both base and noble. DMG will also detect Pd. If you run contacts regularly DMG should be on your shopping list. Expecting them to come clean from dissolving once may be difficult to achieve.


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## goldsilverpro (Apr 25, 2010)

I can't imagine nickel being a problem.


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## machiavelli976 (Apr 25, 2010)

the solution being too concentrated won't allow large silver crystals growing. reminds me the silver dropping with copperas. the more concentrated the solutions the fine was dropping the silver. the finest black silver was almost imposible to settle. the only thing i know about orange colour dealing with silver contacts is cadmium oxide.


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## qst42know (Apr 25, 2010)

Perhaps more likely Pd?

Clipped from the wiki for palladium nitrate.



> The nitrate crystallizes as yellow-brown deliquescent prisms. Alternatively, the compound may be obtained by reacting palladium metal with nitric acid.


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## machiavelli976 (Apr 25, 2010)

qst42know, i am sure you are right even i haven't met Pd in contacts yet. i have some small trapezoidal pieces from an edge connector instead. tomorrow i'll soak them in nitric. you make me courious.


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## metatp (Apr 25, 2010)

Here is a follow up with picture of what things looked like when I started and where things are now.


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## lazersteve (Apr 25, 2010)

Collect some of the cemented powder and redissolve in nitric then test a sample for silver with a drop of HCl (white curd = positive) and for Pd with DMG or stannous.

If copper caused it to cement, it is very likely precious.

Steve


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## metatp (Apr 26, 2010)

lazersteve said:


> Collect some of the cemented powder and redissolve in nitric then test a sample for silver with a drop of HCl (white curd = positive) and for Pd with DMG or stannous.
> 
> If copper caused it to cement, it is very likely precious.
> 
> Steve


I tested the cement, and it has silver as expected. I also added HCL to the cement, and it dissolved a lot of it with a strong reaction leaving the familiar silver colored cement I an used to. I assume that was dissolved in HCL is not precious. I got nothing with the Stannous.

I also noticed that the HCL dissolves the contacts a little as well and I think it is leaving the silver behind. I will check tomorrow.

Thanks all.

Tom


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## qst42know (Apr 26, 2010)

Tom. 

Is your stannous fresh? Have you checked it lately? It's not always conclusive for palladium.

Clipped from the wiki.


> Palladium dissolves slowly in sulfuric, nitric, and hydrochloric acid.


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## goldsilverpro (Apr 26, 2010)

That next to the last photo (the yellow stuff in the jar) looks to me like tungsten might be involved. Silver/tungsten contacts are fairly common, although I haven't seen them in that configuration. If you have some 30% hydrogen peroxide, put one of the points in a little of it and see what happens. You might warm it just a slight bit. If it's tungsten, the reaction might be vigorous, once it gets going.

Also, how difficult is it to cut a sliver off the edge of a point (held with pliers) with a pocket knife? Silver is fairly easy. Tungsten/silver is almost impossible.


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## metatp (Apr 26, 2010)

qst42know said:


> Tom.
> 
> Is your stannous fresh? Have you checked it lately? It's not always conclusive for palladium.
> 
> ...


I wondered the same thing, so I made a fresh batch. Still nothing. The Stannous was positive for a sample of Gold I found recently. I've have to get so DMG though. These contacts are over 40 years old and appear to be used for high heat application I think.


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## metatp (Apr 26, 2010)

goldsilverpro said:


> That next to the last photo (the yellow stuff in the jar) looks to me like tungsten might be involved. Silver/tungsten contacts are fairly common, although I haven't seen them in that configuration. If you have some 30% hydrogen peroxide, put one of the points in a little of it and see what happens. You might warm it just a slight bit. If it's tungsten, the reaction might be vigorous, once it gets going.
> 
> Also, how difficult is it to cut a sliver off the edge of a point (held with pliers) with a pocket knife? Silver is fairly easy. Tungsten/silver is almost impossible.


I've always guessed that these are Tungsten since others I received from the same person are tungsten/silver composite (about 60% silver). They are nearly inpossible to cut. There are also difficult to break except at the angle. What would cause the strange reaction while dropping with copper? Is it a tungsten oxide? It appeared to dissolve in water and react strongly with HCL. After filtering and washing in HCL, I cemented about 83g of grey (mainly silver) powder. I will try the hydrogen peroxide today.

Thanks,
Tom


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## goldsilverpro (Apr 26, 2010)

I'm not suggesting to use the H2O2 as a recovery method (although it might work), but only as a test for tungsten. I seem to remember that the H2O2 got so hot that it rapidly decomposed and I had to keep starting over with fresh. Maybe if you used an icewater bath to keep it cool, it might work.

I've fiddled with the W/Ag points, but never came up with a decent refining method or, at least one that wasn't a total pain. Tungsten chemistry is a bit strange and I was never interested enough to spend enough time to learn it. I'm thinking I just saved up the W/Ag points up and eventually sold them as is.

Harold came up with a process for them and ran a ton of them, as I recall. I think he just cooked them forever in nitric and water until all the Ag was leached out. That's probably the best way because, even if the W is dissolved in H2O2, you'll still have to dissolve the remaining Ag in nitric, anyway. Might as well do it to start with and eliminate the cost and time and aggravation involved in using the H2O2. 

If you go through his posts, I think you'll find that the colors and precipitates you are experiencing are the same as what he has described.
http://www.goldrefiningforum.com/phpBB3/search.php?keywords=tungsten+silver+contacts&terms=all&author=Harold_V&sv=0&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search


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## metatp (Apr 26, 2010)

goldsilverpro said:


> I'm not suggesting to use the H2O2 as a recovery method (although it might work), but only as a test for tungsten.


That's what I thought you meant. There just seems to be 2 different types of Tungsten contacts. Ones that stay intact that stay black, and ones that turn tanish and make a mess of things.



goldsilverpro said:


> I'm thinking I just saved up the W/Ag points up and eventually sold them as is.


That's what I was doing, but I thought I would give it a go again since I have some nitric acid.



goldsilverpro said:


> If you go through his posts, I think you'll find that the colors and precipitates you are experiencing are the same as what he has described.


These posts were his response to me for some other contacts that I sold as is. This new batch reacted quite differently when cementing with copper. It was similar in a lot of ways, but outcome of the reaction was a lot different. I think I may have had too much used nitric acid. I did not heat up it up when dissolving the contacts. They just sat for a few days. When I adde some HCL, the precipitent started dissolving, but I also got some of that not so nice brown fumes. The next small batch I am doing does not seem to be as bad.

I will "test" the contacts with some peroxide. Thanks for the tip.

Tom


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## machiavelli976 (Apr 26, 2010)

there are at least three types ofsilver/tungsten contacts. the nearly black type is the spark savior for the main contacts involved in high currents breaking. it has the lowest ammount of silver and doesn't worth recovery.


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## metatp (Apr 27, 2010)

goldsilverpro said:


> I seem to remember that the H2O2 got so hot that it rapidly decomposed


Thanks for the info GSP. The contacts react very strongly in hydrogen peroxide. Another confirmation of tungsten. 



machiavelli976 said:


> there are at least three types ofsilver/tungsten contacts. the nearly black type is the spark savior for the main contacts involved in high currents breaking. it has the lowest ammount of silver and doesn't worth recovery.


I tend to agree.


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## qst42know (Apr 27, 2010)

Rather than starting with digesting the silver. Will strong peroxide leach the tungsten from the contacts leaving the silver intact?


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## machiavelli976 (Apr 27, 2010)

i have the feeling that strong H2O2 will dissolve everything. despite the low reactivity of the two metals remember there are not melted as an alloy but synthered. the process with H2O2 or some other reactant should be much complicated by the mini-piles taking birth between the grains of both metals.


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## Platinum (Apr 27, 2010)

machiavelli976 said:


> i have the feeling that strong H2O2 will dissolve everything. despite the low reactivity of the two metals remember there are not melted as an alloy but synthered. the process with H2O2 or some other reactant should be much complicated by the mini-piles taking birth between the grains of both metals.



What ?


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