Can't seem to get a complete drop with SMB

[2002valkyrie]

I am not complaining about the drop I do get as the drop is quite clean, but the solution after the drop still shows to have some gold suspended in it. This has happened with 4 out of 4 batches. I end up with 12 cups of super strong SMB solution that test positive for gold. I have let one of them set with copper in it for 3 weeks and it still test positive for gold. Is this something that is to be expected? Should I use something else to drop the remainder? I know it is not due to unused Nitric because the copper would have taken care of it... Wouldn't it? Any sugestions before I drown?

 

[lazersteve]

Valkyrie,

Are you sure it's a positive test for gold and not the excess SO2 and tin precpitating a base metal? If you smell a faint odor of rotten eggs when you add the stannous to the test sample this is likely the case. The rotten egg smell is hydrogen sulfide (very deadly stuff!!) formed by adding a base metal higher than hydrogen in the activity series to sulfurous acid and hydrochloric acid. The sulfurous acid is formed when excess SO2 is absorbed into the HCl and water. Hydrogen sulfide will precpitate many different metals from solution.

Try testing the solution with Ferrous Sulfate and see if you still get the positive result.

Steve

 

[2002valkyrie]

Thanks Steve, that would explain alot but I must have missed the rotten egg smell due to the SMB burning my nose. I've not come up short on my gold and could not figure what it wasin the solution. I will test it with Copperas before pouring it on stumps though.

 

[qst42know]

Pouring your wastes on stumps may well get you in legal trouble, and the copper content might just prevent the stumps from breaking down.

 

[2002valkyrie]

Sorry... I was joking.