Green sludge

[Invisible]

To recover gold from gold plated pins i made aqua regia after reaction add urea to neutralize and then add smb to drop gold and I got this material. Anyone can tell me what is this.
Thanks in advance

 

[Lino1406]

Copper chloride, possibly with gold - excess SMB was used

 

[g_axelsson]

Can also be urea, does it dissolve in water?

Göran

 

[ChemGeek]

It is difficult to say, what it is.
Take sample of solid and stirr for a while in water. If it dissolves, it is excess of sodium metabisulphite or of urea. Possibly urea nitrate if much of nitric acid was left.
If product is not soluble in water it could be at least partially tin related nuisance albeit it looks a bit too solid and well settled.
Some pins are made of phosphor bronze. This contains tin and will cause trouble.

 

[Geo]

Not one mention of testing. Was there gold in solution? Was there a test after trying to precipitate? How much weight in pins are we talking about? Were they fully plated? Why try to dissolve the pins in AR? How many more do I need for twenty questions?

 

[Syn]

This is not an advise, just the way i would go. (Creating lots of waste once again.. learn from mistakes)

Washing/dissolving/filtering using:

1. Hot water
2. Hotter water
3. Water
4. Concentrated acetic acid
5. Hot dilluted acetic acid
5. Concentrated acetic acid
6. HCl bath


Everything not filtered out is most likely waste. //deleted//

 

[g_axelsson]

Syn, why acetic acid instead of HCl?

Göran

 

[Syn]

I guess that there are salts undissolvable in water and HCl present.
Acetic acid worked for me, just be careful with the fumes - use extra bottom ventilation/digestor if needed.

 

[Syn]

Any progress here dear Invisible?