So, proof of concept result here! I was watching Sreetips older vid of him testing if hot sulfuric acid could dissolve gold at all, and watched as it merely TRANSIENTLY dissolved a smidgen of gold, only to redeposit it almost instantaneously on larger gold particles present, until much of the powder eventually merged into a couple large blobs.
I realized this could be a simple way to recover nanogold, which often forms when dropping gold from a dilute solution with metabisulfite. Since adding SMB causes the formation of sulfuric acid, and in a properly denoxed solution, there should remain a mix of HCl and sulfuric acid, I hypothesized that a similar effect could occur if this nanogold suspension with gold powder at the bottom of the beaker was gently simmered.
So, I had a tiny gold drop to perform, and deliberately added only about 80% of the SMB I calculated would be required, dropping most of the gold. Then I added the rest of the SMB a day later, and formed the reddish nanogold suspension (after allowing it to settle overnight again).
Then, I gently simmered it for about 2 hours. EUREKA!!! The solution became cloudier and cloudier as it simmered, then suddenly began to clear up and became very pale blue-green once cooled! All the nanogold had collected onto the gold powder and settled out! The gold powder particles have also become much larger, and made it VASTLY easier to wash as an additional bonus, since it settled out swiftly when disturbed (in only seconds!) and didn't float upon the surface tension.
Here are two pics taken just after the simmering. The solution went from the color of strong black tea (reddish-brown) to this pale color, which became totally clear once it had cooled and all the powder settled.
I realized this could be a simple way to recover nanogold, which often forms when dropping gold from a dilute solution with metabisulfite. Since adding SMB causes the formation of sulfuric acid, and in a properly denoxed solution, there should remain a mix of HCl and sulfuric acid, I hypothesized that a similar effect could occur if this nanogold suspension with gold powder at the bottom of the beaker was gently simmered.
So, I had a tiny gold drop to perform, and deliberately added only about 80% of the SMB I calculated would be required, dropping most of the gold. Then I added the rest of the SMB a day later, and formed the reddish nanogold suspension (after allowing it to settle overnight again).
Then, I gently simmered it for about 2 hours. EUREKA!!! The solution became cloudier and cloudier as it simmered, then suddenly began to clear up and became very pale blue-green once cooled! All the nanogold had collected onto the gold powder and settled out! The gold powder particles have also become much larger, and made it VASTLY easier to wash as an additional bonus, since it settled out swiftly when disturbed (in only seconds!) and didn't float upon the surface tension.
Here are two pics taken just after the simmering. The solution went from the color of strong black tea (reddish-brown) to this pale color, which became totally clear once it had cooled and all the powder settled.
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