Depopulating with HCl

[Marcel]

Soaked in some memory boards which fingers had been processesed earlier in HCl.
Let it get hot then stand over night. Now I have all the boards covered with white needles. I also think I see small silver particles in the solution floating around.
Is the white stuff also silver ? Elementary?

 

[Geo]

white needles? sounds like lead chloride crystals.

from wiki.
In solid PbCl2, each lead ion is coordinated by 9 chloride ions – 6 lie at the apices of a trigonal prism and 3 lie beyond the centers of each prism face. The 9 chloride ions are not equidistant from the central lead atom, 7 lie at 280–309 pm and 2 at 370 pm.[2] PbCl2 forms white orthorhombic needles. While Lead(II) chloride is abundant in many natural water reserves, it is unsafe for human consumtion and must be filtered out
Vaporized PbCl2 molecules have a bent structure with the Cl-Pb-Cl angle being 98° and each Pb-Cl bond distance being 2.44 Å.[3] Such PbCl2 is emitted from internal combustion engines that use ethylene chloride-tetraethyllead additives for antiknock purposes.
The solubility of PbCl2 in water is low (9.9 g/L at 20 °C) and for practical purposes it is considered insoluble. Its solubility product constant (Ksp) is 1.7×10−5. It is one of only four commonly insoluble chlorides, the other three being silver chloride (AgCl) with Ksp = 1.8×10−10, copper(I) chloride (CuCl) with Ksp = 1.72×10−7 and mercury(I) chloride (Hg2Cl2) with Ksp = 1.3×10−18

 

[Marcel]

Here is a picture of the beacon:





Lead chlorid makes sense. Since the HCl dissolves the solderpaste which is usually composed of +95% tin, some lead and 2% silver.
I read that HCl does not affect silver, so it must come out in elemetary form.
So just have to part the silver particles from those lead"needles".
And wiki says lead chlorid forms cristal as needles.

Edit:
As I read, lead(II)chlorid dissolves in concentrated HCl. So I will collect all the solids then try to use hot HCl to dissolve the lead(II)chlorid and filter the rest, which hopefully is plain silver then, because silver is not dissolved by HCl. Correct?

 

[Geo]

a better way may be to collect all the powder and crystals and then incinerate all of it and the digest in nitric acid. you can then cement the silver on copper. if the crystals will dissolve with hcl, it may work but you will still have some lead in the silver.

 

[Marcel]

Thank you Geo. I gave up on recovering, since it just does not seem to be economical and also the mass is rather low.
A bit off-topic: Is there a way to avoid the grey cementing on the gold plating, when using HCl to remove solder from pins?

 

[Geo]

no, not really. though you can remove it by physically rubbing them. after you rinse them well, dry them and place the pins in a piece of cloth (i use terry cloth) and rub them between your hands. it doesnt remove it all, but the gold color comes back through. the grey material is lead and tin so the cloth should not be re-used or washed with other laundry.