separating gold and silver from high concentrations of lead

[goldenqu]

I have bullion. with the following values
70g per tonne au
18.8kg per ton ag
lead above 70%

what is the best method of recovery for gold and silver?
cupellation
nitric acid

what is the best way to remove lead bullion

 

[nickvc]

Welcome to the forum.
The process that leaps to mind is the Parkes Process which involves adding zinc to molten lead to absorb the silver and gold which is then skimmed from the surface. If you research into it on the internet I'm sure you will find plenty of information to guide you and if you have any questions about it I'm sure someone here on the forum could help.

 

[g_axelsson]

70% lead, 2% silver and minor amounts of gold. What makes up the last 30%?

/Göran

 

[Geraldo]

70% lead, 2% silver and minor amounts of gold. What makes up the last 30%?

/Göran

+1 on this.

For a lead bullion assay, I would want numbers for Pb, Cu, As, Sb, Sn, Tl, Te, Bi at a minimum. All those other elements will need to be taken care of before using Parkes.

If you have small amounts of bullion, then you could try the common smelter approach for a silver refinery, which is cupellation. Note that requires a lot of steps, great ventilation, fume capture (baghouse and scrubber of some sort) and if you do it wrong you risk losing a lot of precious metals. Another approach is to use Betts Lead Electrorefining and carefully collect the slimes for PM recovery. If you use very "dirty" lead for that, it will be troublesome, but possible.

There is a thread on recovering PMs from lead bullion here:
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=86&t=11029&hilit=betts

and there are probably several others.

Best Regards, Geraldo