# Precipitating Silver Chloride from Silver Nitrate



## doesn'tmatter (Feb 13, 2018)

Hello all, 

This is my first post on the forum. My question is all those members who have experience scrapping of silver from silver coated scrap. 

I have been trying to scrape off the silver coated on a copper base and have done the following experiment multiple times but barely see any result:

1) Approx. 100 g of silver coated scrap is dipped in 20 mL Nitric (AR grade, 70%) and Distilled water (20 mL).
2) I heat the solution until all the brown gas (NO2) is eliminated.
3) Then I let it sit for like 5 min. 
4) Add a pinch of table salt (sodium chloride)

But I am NOT seeing any milky precipitating activity going on! Instead, I see those salt granules turn green just for few seconds before they dissolve in solution. Does anybody know where I might be going wrong? I am 100% confident that the metal coated is silver only as I got it chemically tested at a lab. Please share your experiences if you have dealt with this stuff before. Thanks!


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## nickvc (Feb 13, 2018)

Welcome to the forum.
Unless you are fully dissolving the copper the chances are that the silver is cementing back onto the exposed copper, this material would be ideal to use for cementing silver nitrate solutions as the silver would be recovered for free but trying to strip it is not going to be easy or very profitable.
The easiest method would be to build a copper cell and recover the silver from the slimes but this is dependent on how much you have and how much silver is actually plated onto the copper base.


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## Yggdrasil (Feb 13, 2018)

Hi!
I just pondered, if you add NaCl to the Nitric or make a weak AR during dissolving.
Would the Silver precipitate as Silverchloride directly or would the preference be towards cementing anyway?
Even if the preference is towards cementing, one would hopefully not need to dissolve all the copper.
Or am I completely off the track here?

Br Per-Ove


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## g_axelsson (Feb 13, 2018)

Yggdrasil said:


> Hi!
> I just pondered, if you add NaCl to the Nitric or make a weak AR during dissolving.
> Would the Silver precipitate as Silverchloride directly or would the preference be towards cementing anyway?
> Even if the preference is towards cementing, one would hopefully not need to dissolve all the copper.
> ...


It would directly turn into silver chloride and cover the object, passivating the surface. The reaction stops and instead of a silver coated object you now have a silver chloride over silver coated object. That is why you have to inquart gold alloys with too much silver in it.

Göran


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## Yggdrasil (Feb 13, 2018)

Hmm!
I knew there had to be a hitch, seemed too easy, now I remember why 
But then, if I remember correct, Lou talked about using straight AR but with tumbling or some mechanic manipulation that broke the surface layer.
This could be done here too, if the pieces are small enough, at least the concept may work.

BR Per-Ove


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## Topher_osAUrus (Feb 13, 2018)

Yggdrasil said:


> Hmm!
> I knew there had to be a hitch, seemed too easy, now I remember why
> But then, if I remember correct, Lou talked about using straight AR but with tumbling or some mechanic manipulation that broke the surface layer.
> This could be done here too, if the pieces are small enough, at least the concept may work.
> ...



I believe that post was in referendum to karat scrap being dissolved without inquartation or upgrading the scrap, before dissolving in AR. - I could be, and have been wrong before though

The problem, or major problem, with silver plated stuff is its base metal core. Some (primarily) is copper, or brass, or bronze, or I have even seen some lead core stuff once. So what nick mentioned initially is why its not really a good idea to use straight nitric. Cementation fighting dissolution (and winning - since the core is more reactive than the silver.)

The old books mention using a pretty nasty concoction of sulfuric and nitric heated up to a hellish temp to strip the silver down to the base metal. In a couple books I have, they sub the nitric and use a nitrate salt instead. It can be used at room temperature but it slows down to a crawl, and to double up the inefficiency, the solution also needs to have the silver dropped quite often (since its only like 5% nitric, if you are using a litre of the entire solution, the amount of silver that can be held in solution from the incorporated nitric is quite small -insert math here-)
They then used the salt method to recover the silver (see where another problem is?)
adding too much salt, will make a pretty hardcore AR that has a HUGE amount of sulfuric in it.


As I see it now, recovering silver from silverplate would not even become a break even venture until silver spot price went to around $100 an ounce..


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## Yggdrasil (Feb 13, 2018)

That is true.
Lou's post was regarding karat scrap, but won't the passification layer issue be the same?
If you managed to get the pieces small enough and tumble it in AR or Nitric/salt mix, some how.
Then the mechanic manipulation might overcome the layer pacification and create Silver Chloride?
Am I totally in space here?

Mind you, I have not processed Silver, just thinking out loud ;-)

Bye the way, have anyone tested the water cell on a larger scale?
https://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=25296


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## Topher_osAUrus (Feb 13, 2018)

Yggdrasil said:


> That is true.
> Lou's post was regarding karat scrap, but won't the passification layer issue be the same?
> If you managed to get the pieces small enough and tumble it in AR or Nitric/salt mix, some how.
> Then the mechanic manipulation might overcome the layer pacification and create Silver Chloride?
> Am I totally in space here?



Yes, it is the same, to a certain extent, but it it also totally different.

Karat scrap, the silver chloride is blocking the acids action on the gold that is interspersed with the silver (and little bit of copper), with the silver plate spoons, the silver chloride is blocking more silver and LOTS of copper. So if the silver chloride keeps getting broke free, eventually it is going to get to the copper and when it does, that is going to take preference to be dissolved. 

So, if there is one tiny little hole where the acid can get to the base metal and it will quickly go to work. Then you will have a mess of silver chloride, silver metal and a solution of copper. While that doesn't seem like too big of a deal, that's just one big mess (sounds like to me anyways).

I'm sure to that "certain extent" mentioned earlier, it would work. But, it sounds like a whole big deal of waste to treat for some pennies worth of silver. It would probably cost 5x the money gained to treat all the waste responsibly. 

As far as the water cell, I have not tried it. I have a whole bunch of stuff I want to try, that being one of them, but because of the cold weather and tolls I have, I just haven't had time to play like I want to.


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## doesn'tmatter (Feb 13, 2018)

nickvc said:


> Welcome to the forum.
> Unless you are fully dissolving the copper the chances are that the silver is cementing back onto the exposed copper, this material would be ideal to use for cementing silver nitrate solutions as the silver would be recovered for free but trying to strip it is not going to be easy or very profitable.
> The easiest method would be to build a copper cell and recover the silver from the slimes but this is dependent on how much you have and how much silver is actually plated onto the copper base.



Now that I think of it, it does make sense that silver is cementing back on the exposed copper. This would also explain turning of sodium chloride particles turn green due to excess copper in the solution turning it into copper chloride! 

I just dissolved a small piece of scrap (hardly a gram of silver) in my first attempt and maybe that's why I did not see cemented silver onto the copper surface. In my next attempt, I would push it to 500 g worth of scrap with approx. 10 g silver. I hope that's enough to be actually filtered. 

My question is now is, though, what would be the best way to filter out silver cementing on the copper material and also some of it present in the solution. Should I simply wash the scrap with water once the silver layer is dissolved in acid? Then later also filter the solution. Also, what is the ideal type of filter paper specifically for silver particles to look for? Thanks!


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## geedigity (Feb 14, 2018)

Silver plate is usually fairly thin. In fact, it is very thin. This in itself makes recovery of silver plate a losing proposition. Nick has the best idea, use the silver plated items to cement out silver nitrate, since eventually the base metals will all dissolve. To help the reaction along, it would be best to scarify the silver plate to expose some of the base metals. A grinder or dremel would work.


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## doesn'tmatter (Feb 14, 2018)

geedigity said:


> Silver plate is usually fairly thin. In fact, it is very thin. This in itself makes recovery of silver plate a losing proposition. Nick has the best idea, use the silver plated items to cement out silver nitrate, since eventually the base metals will all dissolve. To help the reaction along, it would be best to scarify the silver plate to expose some of the base metals. A grinder or dremel would work.



I agree. I might even some add some granulated copper powder that I have for initial attempts. Thanks!


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## goldsilverpro (Feb 14, 2018)

Extremely thick silver plate (.001") is only worth about 9 cents per square inch. Much of the silver plating is about 1/5 of that. Actually, there is really no profitable way I know of for the small hobbyist refiner to strip normal silverplate. 

To strip silver plate from a copper alloy base, nitric acid won't work, unless you dissolve everything, including the copper base. Why? Because the dissolved silver will cement, or plate back onto the copper. If you dissolved solid sterling silver with nitric, yo normally use a copper bar or pipe to cement, or plate out the silver as a gray powder which looks like wet cement. Thus the name.

Silver chloride, itself, will never turn green unless it's mixed with another solid that happens to be green. It is white unless you put it in the sun, in which case, it can turn purple. When dirty, it can take on the color of the dirt.


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## tortuga09 (Feb 14, 2018)

Bonsoir.

l y a bien une solution acide nitrique + acide sulfurique ,

Comme dit plus haut très peu d'argent en moyenne 2,91%.

d'argent.
Good evening.

There is a solution of nitric acid + sulfuric acid,

As said above very little money on average 2.91%.

silver.


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## nickvc (Feb 15, 2018)

tortuga09 said:


> Bonsoir.
> 
> l y a bien une solution acide nitrique + acide sulfurique ,
> 
> ...



Be aware that mixture is very nasty and not something I personally would be happy to work with.


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## goldsilverpro (Feb 15, 2018)

The 95/5, sulfuric/nitric solution, heated to about 82C, was designed for removing faulty silver plating so the parts could be replated. It's a very dangerous solution to use. It's also a chore to collect the silver from the solution. When I did run it, it was usually at room temp. Quite slow, but much safer.


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## tortuga09 (Feb 19, 2018)

goldsilverpro said:


> When I did run it, it was usually at room temp. Quite slow, but much safer.


Yes


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## Barth Tholomew (Aug 22, 2022)

Why was it such a chore? Copper cementing not an option?


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## orvi (Aug 22, 2022)

Barth Tholomew said:


> Why was it such a chore? Copper cementing not an option?


If you are about to scavenge the silver from this "deplating" solution, you will need to dilute it. And diluting sulfuric acid in bulk quantity is nasty and very dangerous operation.

Copper cementing, I would be cautios also with this, as copper passivate in enviroment of strong sulfuric acid - that is why the sulfuric acid is used for de-plating - because nitric acid stops at the passivated copper surface. So I do not think this would work well.


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## Abdoulapapatte (Sep 21, 2022)

hello I advise you to use electrolysis with a salt solution for electrolysis

a beaker

on the anode side the cover has moved

cathode side a stainless steel knife blade

recommended current 3.5 volt low amperage



I run past the anode side, the silver goes away, the chlorine recovers it then it oxidizes by falling into the bottom of the beaker, on the other side the stainless steel oxidizes, simpler in your case


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## Yggdrasil (Sep 22, 2022)

Abdoulapapatte said:


> hello I advise you to use electrolysis with a salt solution for electrolysis
> 
> a beaker
> 
> ...


When it already are in solution there are no need to use electrolysis.

Edit spelling


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## Mudville9 (Sep 22, 2022)

Some information from the Polish refiner KGHM. 
Not sure if it has been posted before.


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## Abdoulapapatte (Sep 29, 2022)

hello you dont need nitric only water and salt same resulte


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