# Mobile phones - where is silver?



## alpha (Jan 6, 2013)

According to some 30 publications, mobile phones (including battery) contain:
- Au 250-350 g/ton
- Ag 2000-3500 g/ton
- Pd 80-120 g/ton

After processing some 40Kg, gold and palladium figures look more or less ok. Silver looks absent.

The processes have been:
1) Hi Cl method to dissolve silver (Song et al. - 1995)
- battery & plastic shell removal
- crushing + incinerization
- hot (70 C) HCl for 24hr with liquid/solid= 2/1
- two times AP + bubbles for 24hr with liquid/solid 2/1
- Poor man AR saturated with table salt with liquid/solid 2/1
(gold & Pd recovered with figures consistant to the publications)
- Both AR and AP after diluition showed just a little white opaque silver chloride at the bottom of the beaker (after 2days)
Than
- Ammonia added to the solid residue for 24hr + stirring
- Solution filtered and Cl added (table salt) nothing precipitated

2) Sulfuric Acid + Nitric
- battery & plastic removal 
- crushing + incinerization
- Sulfuric Acid + Hydrogen Peroxide for 24hr with liquid/solid = 2/1
- Nitric 30% for 24hr (4-5times until nothing else was dissolved by nitric) - Silver sulfide/sulfate should be dissolved by nitric
- Solution filtered and Cl added: very little white opaque silver chloride at the bottom of the beaker (after 2days)
(than the solid residue treated with AR to recover gold)

3) as above without Sulfuric Acid only nitric (same result: no silver)

4) Same of n.1 but with "very poor man AR" done with Ammonium Nitrate instead of Sodium Nitrate (it looks more powerful)

Except for n.4, I have verified that all the solutions were actually able to dissolve silver (the solutions that are supposed to dissolve mobile phone's silver).

The question is: am i loosing something or the university publications contain some mistake? ...maybe a typo error with a couple of zero added in the silver figure)

This is my first post and I wish to thanks to everybody of the forum, it is a couple of years I'm enjoining in refining electronic scraps (It is just an hobby for me) and this forum is plenty of usefull informations. I would be happy to share all the pubblications I have... any con?
I wish you a properous and happy 2013.
/A


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## butcher (Jan 8, 2013)

I Guess what comes to my mind when I looked that over,

(1) They form insoluble silver chloride, and also speak of poor mans nitric which would form silver sulfate.
Silver sulfate will not dissolve in ammonia.

(2) They form silver sulfate also.

(Some of this looks like they may have collected information or techniques from our forum, reading the publications could reveal this suspicion)


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## Meh1 (Feb 6, 2013)

I have to agree with butcher. This seems like a round about way to recover any PMs INHO. Although sound chemistry. One question comes to mind though why worry about the tiny amount of silver you'll recover when you've successfully recovered gold and platinum from your material? In my own humble and novice experience I haven't recovered all that much silver from cell phones. Maybe I am wasteful but I feel content recovering gold and platinum from cell phones. Then again I get them for free (last batch was 55lbs without batteries or backs ). Good work though man..seems like youve done your homework.


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## nickvc (Feb 7, 2013)

As Butcher pointed out any silver in the scrap would have formed silver sulphate or silver chloride.
The only ways I know to recover the silver is either nitric acid which will also dissolve the palladium or hot concentrated sulphuric, nasty, which will dissolve the silver but both methods will require more processes to get pure silver. The mix of elements and metals on the boards are the real problem for the home refiner because after each acid process incineration would ideally be required especially if tin happens to be one of those metals so I think the idea of recovering all the values might become troublesome especially in volume, these boards are treated the same as the other boards I'd guess by the big boys who would crush, sieve and then melt into dore bars to be refined at a copper refinery so separating the values isn't a problem for them. In my opinion you could spend more time and money chasing the silver than it's worth unless you have a large ready set laboratory if your doing these in any volume, just recover the gold and palladium they are comparatively easy so long as you get rid of that tin.


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## alpha (Feb 10, 2013)

Hi all,
thanks for the replies... and apologies for my late relpy.
I am still struggling to extract silver from mobiles PCB in my home-made lab but still nothing. At the moment working some Li ion batteries, just to exculde the presence of silver in the batteries (with the risk to remain with a strange sleeping face for lithium salts intoxication... :roll: )
About the silver content: if it is actually ten times the gold content and the value of silver is one fifty... It means silver represents 20% of the metal value of a mobile PCB. Actually it does not worth the effort if somebody has to use lab/industrial grade nitric. Nor all the precautions or safety issues to use CN.

The most promising is to use hi cl concentration acqua regia, as per an article i've found (attached). this method goes against the good sense and against everithing you can read on this forum... I suggest you to read it.

About the silver sulphate formation I definetly agree.

What looks odd are many PH degree works and university articles (you can download from the network or I can post them) stating to extract silver from mobile phones by simple acqua regia... Mah... maybe looking for funds...

Thanks to all


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## johnny309 (Feb 11, 2013)

Silver is ussualy in solder(Sn96,5 / Ag3 / Cu0,5)....and the rest is in MLCC.....
Yes you can use AR to dissolve the gold and palladium...and make AgCl,then filter,wash with water and reconvert to Ag with methods allready on this forum.
But is a catch...MLCC is a multilayer device (and the board is also a multilayer type)....so you will not recover all the silver without crushing to fine powder.
And not to mention the formation of SnCl....witch will make colloids and ...


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