Using SMB to force the drop by using up the Chlorine

[Anonymous]

Ok, I'm not looking for a shortcut here. I've been experimenting though and I guess I'm looking for one of the good chemistry heads to correct or confirm my theory.

Standard drop method from acid/bleach - warm, and let chlorine be given off, then let cool and use SMB to drop the gold. Works perfectly of course and I get clean gold every time from fingers.

Also it seems to work cold straight from the filtered solution by dropping a larger quantity of SMB in and letting the solution "cycle" by dropping and redissolving the gold until the chlorine is all used up. The problem being that when the gold drops using this method, it seems to pull down any copper that's in solution resulting in "dirty" gold that needs cleaning up.

Is my understanding of the second scenario correct? Does this "forcing" pull the copper out?

Regards

Jon

 

[Lino1406]

SMB will react 1stly on gold and chlorine.
Copper as CuCl comes next

 

[kkmonte]

Well you should really try to eliminate the copper prior to dissolving with HCl/Bleach (that's what the HCl rinses are for). Even if let it cool, and do it in your "first" method, any Copper in the solution should be dropped as well. I don't think its the gold "cycling" that is causing the copper to come out..