# Black Powder Dropping



## metatp (Apr 19, 2010)

New question for those that know about refining silver with the silver chloride method.

I bought a couple of bars of silver that I was told were made by refining to silver chloride before melting into these bars. They tested to be high silver content use a silver acid test. I don't know much more than that.

When I started dissolving in nitric acid, I start seeing this black powder drop while the silver was being dissolved very slowly. I am using a mixture of about 30% nitric acid (70%) / 70% distilled water. The silver is very shiny with black powder also dropping. The reaction is still progressing, so I want to wait until the nitric acid is used up before I start testing. My question is, does anyone know if there is anything in the silver chloride that would lead to this black powder? I am not ruling out carbon, but it drops right to the bottom without the usual mixing in the solution before settling.

Thanks,
Tom


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## goldsilverpro (Apr 19, 2010)

To convert AgCl to Ag in a melt, they would usually use sodium carbonate, although it's normally a lousy way to do it. If the AgCl originally came from dissolving karat gold directly in AR, there could have been some undissolved gold mixed with it. When the AgCl converted to Ag and melted, the gold would alloy with it. In other words, the black could possibly be gold. It seems quite heavy from your description. 

I'm not saying that is definitely gold. Just that it's possible, especially if it came from karat gold. It could be something else that's not soluble in nitric. It would be interesting to know the source of the AgCl.

The only thing wrong with this gold theory is that, after dissolving the silver, a small amount of gold is usually so finally divided that it becomes purplish (colloidal) and doesn't settle very well at all. However, if there is a lot of gold, it could be black and settle fast. 

I once worked for a guy that specialized in silver. He often ran the AgCl, in large quantities, for other refiners, that was generated from doing karat gold directly in AR. He heated it slowly in a furnace with sodium carbonate and ran the resulting silver metal through a silver cell. It was amazing how much gold he got from it.

Filter some of it and rinse it well to get all the silver nitrate solution out of it. Dissolve some in a tiny bit of AR and test a drop with stannous chloride. It's worth a test.


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## nickvc (Apr 20, 2010)

Im with GSP on this i suspect Au,in the past i bought loads of silver bars from other refiners that contained in some cases considerable amounts of Au which i found amusing as they should have known better,a quick test with a drop of nitric on the bars usually reveals its presence as on sterling it shows a grey colour but the presence of Au seems to give it a more brown /green tinge.You could have your silver for free 8)


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## Oz (Apr 20, 2010)

Do not get too excited (depending on the source of your silver chloride), I recently refined a bar about a half kilo in size that supposedly came from sterling scrap that exhibited the same black powder. I asked the individual that supplied the bar to me for refining to clarify the source material but they had nothing to add as it was a purchase of theirs. I ran the residue in AR to check for values and came up empty. My best guess (I did no further testing beyond the AR check) was that the silver was likely from electrical contacts, not sterling.


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## metatp (Apr 20, 2010)

Oz said:


> Do not get too excited (depending on the source of your silver chloride), I recently refined a bar about a half kilo in size that supposedly came from sterling scrap that exhibited the same black powder. I asked the individual that supplied the bar to me for refining to clarify the source material but they had nothing to add as it was a purchase of theirs. I ran the residue in AR to check for values and came up empty. My best guess (I did no further testing beyond the AR check) was that the silver was likely from electrical contacts, not sterling.


Oz,

My situation is similar to yours. I don't expect to get Gold (but it would be nice). Even if it was from electrical contacts, I don't know what would cause the black powder.

Thanks GSP and nickvc. Though I expect no value from the black powder, I will test it. BTW. Other than the black powder, the solution is clear and the bars in nitric are very shiney (kind of glittery if that is a word). I will let you know what I find in a couple of days.

Tom


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## machiavelli976 (Apr 20, 2010)

Lead !?


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## goldsilverpro (Apr 20, 2010)

Lead will dissolve in dilute nitric.


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## metatp (Apr 20, 2010)

What about any potential salt or oxide that does not dissolve in nitric acid?


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## Irons (Apr 20, 2010)

nickvc said:


> Im with GSP on this i suspect Au,in the past i bought loads of silver bars from other refiners that contained in some cases considerable amounts of Au which i found amusing as they should have known better,a quick test with a drop of nitric on the bars usually reveals its presence as on sterling it shows a grey colour but the presence of Au seems to give it a more brown /green tinge.You could have your silver for free 8)



It's nice to know those refiners were making so much money that they could afford to hi-grade and only process the easy material. :mrgreen:


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## Oz (Apr 20, 2010)

I suspected tungsten as the culprit since it is used in silver contacts and fits the description of what I found in that half kilo bar as to color and acid resistance.


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## goldsilverpro (Apr 20, 2010)

> What about any potential salt or oxide that does not dissolve in nitric acid?


I would think that most salts or oxides would end up in the slag and anything alloyed or included with the silver would most likely be metallic. Carbon is so light that it usually floats on top of the slag.

If the black is tungsten metal, it is readily dissolved in 30% hydrogen peroxide. The reaction can be quite vigorous in quantity.


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## metatp (Apr 20, 2010)

I am quite curious now. I may just filter Thursday whether all the nitric acid is used up or not. I took one of the bars out to look at it. It is very rough like sandpaper, but it is very shiny. I will let you know what I find.


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## nickvc (Apr 21, 2010)

Irons said:


> nickvc said:
> 
> 
> > Im with GSP on this i suspect Au,in the past i bought loads of silver bars from other refiners that contained in some cases considerable amounts of Au which i found amusing as they should have known better,a quick test with a drop of nitric on the bars usually reveals its presence as on sterling it shows a grey colour but the presence of Au seems to give it a more brown /green tinge.You could have your silver for free 8)
> ...


Irons the refiners were usually passing on jewellers waste bars which often contained Au as the staff didnt care about keeping the metals separate, but i was amazed they failed to spot the Au in the assaying process or even check for it.The big boys get loads of free Au from their silver scrap when the buyers dont sort out their scrap properly,the biggest joke is that many people know there is Au in their scrap but are told the cost of recovery makes it uneconomic to recover it :shock:


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## metatp (Apr 22, 2010)

Well, to my surprise. It is gold. I have about 11g of this black powder. That is about 5.5%. I don't know how much of that is gold, but I am very happy with the results.  I still have about 200g of the bars that I have not fully dissolved yet. Maybe I need to start working with gold now. Thanks for every bodies help. Glad i never through it away. Now I need to find where those bars came from. 

On another good note, I just found a couple of white gold earrings in a small batch of silver I got. I don't mind my silver being contaminate with gold. Usually it is nickel.

Regards,
Tom


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## nickvc (Apr 23, 2010)

HTPatch said:


> Well, to my surprise. It is gold. I have about 11g of this black powder. That is about 5.5%. I don't know how much of that is gold, but I am very happy with the results.  I still have about 200g of the bars that I have not fully dissolved yet. Maybe I need to start working with gold now. Thanks for every bodies help. Glad i never through it away. Now I need to find where those bars came from.
> 
> On another good note, I just found a couple of white gold earrings in a small batch of silver I got. I don't mind my silver being contaminate with gold. Usually it is nickel.
> 
> ...


Congratulations i must admit im not surprised, the fact you found those gold earrings in the batch of scrap shows people really dont sort their scrap properly.On a brighter note the Au powder will be at least 95% pure i reckon, it helps cover the fact that stirling scrap rarely reaches 92.5% Ag,mainly due to the solder used, i always work on 90% as the bench mark.


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## goldsilverpro (Apr 23, 2010)

Congrats. It's always nice to find about $385 (possibly) worth of gold in $110 worth of silver. It sounds like you hit a good lick. Doesn't surprise me at all. I've seen this happen many times. Just don't count all your chickens until you have a gold button sitting on the scale.


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## metatp (Apr 23, 2010)

goldsilverpro said:


> Congrats. It's always nice to find about $385 (possibly) worth of gold in $110 worth of silver. It sounds like you hit a good lick. Doesn't surprise me at all. I've seen this happen many times. Just don't count all your chickens until you have a gold button sitting on the scale.


Thanks. To me right now, I am happy with the silver being 94-95% pure (I wonder if I should complain the it is not at least 95% pure silver as advertised 8) ).

I still don't understand how this could happen. I could understand if it were melt jewelry, but this is no traces of copper that I can see, and the gold definitely looked like it was alloyed with the silver.


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## qst42know (Apr 23, 2010)

> I still don't understand how this could happen. I could understand if it were melt jewelry, but this is no traces of copper that I can see, and the gold definitely looked like it was alloyed with the silver.



A bit of mechanical drag down in the silver chloride from gold refining. Or perhaps a small amount of gold work at the silver bench. Or even some jewelery like I have been encountering lately is gold plated 925.

Don't look a gift horse in the mouth just hurry over and see if they have more. :mrgreen: What a pleasant surprise.


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## qst42know (Apr 25, 2010)

Another possible source is a crucibel once used for gold was used to make your silver bar.


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