AgCl in ammonia

[Bluebloomer]

Hello all, a buddy of mine has decided to mess around with some silver he had laying around and asked my help for a problem he created, but his English is so bad, so I ask the question for him.

From what I understand this is what he did:
Dissolved some silver items, rings and coins I believe. He divided the silver nitrate in 2 batches, he wanted to cement the silver out from 1 batch and make silver chloride from the other.
For some reason the put the agcl and the cemented silver together and added dillute ammonia, why I do not understand, he thought he was cleaning it, to get rid of the black residue after using NaOh.

Now he has the problem as you can see in the photo, the black residue is indeed gone, but a pinkish precipitant showed up, with a layer of what I think is elemental silver.

What can he do ? What is the pink precipitant ? And how can it be recovered ? It looks like a nasty problem, silver chloride, silver cement, and silver nitrate, mixed with dillute ammonia..

Oh he freaked out because he did not understand what to do, or how and dunked it all together to melt it and start over.. Guess that's not an option now anymore.. :wink:

 

[g_axelsson]

I would at first acidify it with HCl to avoid the dangers with ammonia forming explosive compounds.

Then you should have silver chloride and silver with a bit of copper from the cementation process.
Pour off the excess liquid and give it a couple of washes.

After this you can use the method of choice to convert the silver chloride to metallic silver, the silver already converted will not interfere.

Göran

 

[Topher_osAUrus]

Did he reacidify the silver diamine?

He mixed the ammonia with some of the nitrate?
Im no pro, but, you could have a nasty explosive compound in the mix now too. And i would certainly start by decanting carefully and reacidifying it (i believe i read that destroys the explosive compound). Then, I think I would treat the solids with NaOH and then melt the silver metal and silver oxide and start over.

 

[g_axelsson]

Add the acid before decanting or you only move the problem to a new beaker. The silver chloride is dissolved in the ammonia, at least some of it.

Göran

 

[Topher_osAUrus]

Add the acid before decanting or you only move the problem to a new beaker. The silver chloride is dissolved in the ammonia, at least some of it.

Göran

Excellent point!

I saw he mentioned it was dilute ammonia, and kind of figured that what little silver was in the household ammonia got dropped out already as the pink precipitant, since he mixed it with the nitrate. I went under the assumption that the nitrate probably removed the silver out of solution. But that is pure conjecture, as the "step by step" is coming not from who did it, but a mediator...and we have all played the telephone game... It only takes one or two people for facts to get flip flopped around

BlueBoomer, did you test the ph at all during any point in time?
Can you now?
Regardless of what it is now, I would certainly do as göran suggested and acidify the solution immediately before doing anything else.

 

[Lino1406]

Note: Wikipedia says silver nitride Ag3N, explodes with acid

 

[Bluebloomer]

Thank for the replies my fellow gold refiners.

The PH paper says it's PH is 13-14 so I assume he did not wash any of the NaOh out.

I have some leftover barren acitic liquid with a PH of 2, should I add it in slow increments, or should I add HCL instead ?

He brought the stuff over to my house, and gave me half the silver I could recover, the whole 1 or 2 dollar, lol

 

[g_axelsson]

Note: Wikipedia says silver nitride Ag3N, explodes with acid

With concentrated mineral acid.
https://en.wikipedia.org/wiki/Silver_nitride

Acidifying removes the risk of creating the explosive, if you have already created explosives then there are other ways of treating it.
Silver nitride is a black substance or creates mirror-like coverings on the inside of vessels.

Interesting article on explosive silver compounds. On Hazardous Silver Compounds, John L. Ennis and Edward S. Shanley 1991.
View attachment [email protected]

Here is a page on safe handling of ammoniacal silver solutions... basically, don't store them!
http://stainsfile.info/StainsFile/stain/metallic/safesilver.htm

... and a thread from GRF : http://goldrefiningforum.com/phpBB3/viewtopic.php?t=944

Göran

 

[Bluebloomer]

Upon acidifying the liquid it got black as tar with a lot of 'flakes' floating around, that is now nicely settled to the bottom of the bucket.

The remaining liquid can now me siphoned off ? And then what would the next step ?

I'll make my buddy poop his pants when I tell him an explosive compound was in the making with what he did, and no idea silver could be that lethal ... :?