bolbol - 19-6-2020 at 11:14
Hi everyone,
I am hoping someone can tell me what I am doing wrong as I am unable to get gold out of solution using SMB.
I have tried this in several ways using crushed gold bearing rocks. Soaked them for a few days in HCl + a bit of nitric acid. I added excess SMB to
the final solution and nothing precipitated out. I did the same procedure again but before adding SMB, I added some sulfamic acid and let the solution
sit for a while as I have heard it reduces nitric acid. Still nothing when SMB was added.
For experiment #2, I did a whole different procedure using actual gold nuggets in AR. This time I added gold in excess and added a few drops of nitric
acid into the HCl and left the solution sitting for about a week. The assumption here is that all nitric was consumed as gold is in excess. I decanted
the solution leaving the solid nugget behind and again tried SMB... and nothing.
Just curious what I am doing wrong here... my SMB is labeled Sodium metabisulfite and it definitely creates SO2 when added to acidic solutions.
I have heard excess nitric is the issue but experiment 2 shouldn't have had any excess nitric in it. Even if it did, wouldn't excess SMB consume it?
Thanks
unionised - 19-6-2020 at 12:29
Does pH make a difference?
draculic acid69 - 19-6-2020 at 16:27
Did u neutralise the aqua regia with urea before adding the SMB? If u have been watching streetips on YouTube he's not great at it and you picked a
bad example to follow. U have to neutralise the aqua regia with urea first. It's necessary and can't be skipped
[Edited on 20-6-2020 by draculic acid69]
barbs09 - 19-6-2020 at 18:03
Does your solution actually have any gold in it? I'd suggest the stannous chloride test. Plenty on the internet, but the Ebook linked to below is
the so called "gold standard" on precious metal extraction.
https://recyclingsecrets.com/free-reports/refining-precioius...
bolbol - 20-6-2020 at 22:16
Used powdered zinc and everything went smoothly.