Precipitating with copper powder

[Martijn]

I would imagine the dissolved copper would make the gold drop out again straight away, at least some of it?

Dissolved copper does not cement out gold. Only metallic copper does.

If you do it right, you leave a bit of gold in solution. So no need to wash traces out. HCl does not dissolve copper btw.
You could get that out with smb, or the stockpot.

The thin copper pcb foil is not a good idea, as kurt described even flattened pipe leaving small bits of copper.

 

[anarxi]

Dissolved copper does not cement out gold. Only metallic copper does.

If you do it right, you leave a bit of gold in solution. So no need to wash traces out. HCl does not dissolve copper btw.
You could get that out with smb, or the stockpot.

The thin copper pcb foil is not a good idea, as kurt described even flattened pipe leaving small bits of copper.

when you dissolve the copper sublayer from the gold-plated fingers on memory cards, using saltwort and an aquarium pump, do the copper pieces float without gold?

 

[Martijn]

when you dissolve the copper sublayer from the gold-plated fingers on memory cards, using saltwort and an aquarium pump, do the copper pieces float without gold?

Hi Anarxi, I was talking about the tiny copper pieces letting go if you use thin foil and no, copper pieces do not float with or without out gold as far as i know, what is your point here? I don't see the relevance, sorry.
Besides that, we often advice not to use a PCB when PM's are in solution, as pm's can get stuck in between the PCB layers if there is copper in between, or if not all copper is displaced, gold can get stuck underneath, and how much fan blades with a very thin layer of copper would you have to make to cement out an ounce?
Kurt advised only solid copper, or fine powder, and advised against using thin copper material.

What is saltwort?

I think for proper cementing with copper powder you need an airlift or a stir bar inside to ensure contact with the salts in solution.

 

[anarxi]

Solyanka is hydrochloric acid.
I use a board blank.
There is either one layer of copper or two if the textolite plate is double-sided.
The copper thickness is about 30 microns.

 

[4metals]

I think there is some translation error going on here. Is Saltwort also Solyanka?

 

[anarxi]

I think there is some translation error going on here. Is Saltwort also Solyanka?

https://en.wikipedia.org/wiki/Hydrochloric_acid