Sulfuric Acid / Black Powder Settle Times

[nickjam]

I purchased some 98% Sulfuric Acid and got my cell (Lazer Steves design) running for the first time. I processed about 2 pounds of saved premium pins. (2 pill bottles)

The gold plated power connectors, drive connection pins on the drives and motherboard. The Wifi card connector in laptops or cellphones, etc.

The cell performed great and was fun to watch. The end result was the classic black thick liquid (sludge). Cleanup included a transfer to a beaker for the Au+Sulfuric Acid (sludge) mixture due to a few pins that landed into the cell out of the bowl. Since this is a new process I want to determine yield, so I know how many pounds are worth doing in the future, 4, 8, 12 for time and $$. I must add at this point, that the solution is not saturated. If I had more the cell could have processed it...

The "sludge" has been resting in the same spot in the garage for 3 days and only the top 1/8" might be clearing. I expected the settling to take a while due to the viscosity and density of the concentrated sulfuric acid, but how long does this take? Most of the posts I read before doing this mention 24-48 hours of rest then siphon off the sulfuric acid for use in further batches. This sludge has not cleared a bit!!!

Thank you for your time and experience.

 

[acpeacemaker]

While it can take sludge 24-48 hrs to settle down. If it doesn't you can add the sulfuric to water (not the other way around) to reduce the density of the solution. You can also regain the sulfuric back by means of slow evaporation. -Not in your garage-

Honestly 2 lbs isn't a lot but it can depend on your setup and vessel size as well.

Andrew

 

[kernels]

I've had pretty good luck with vacuum filtering through a fibreglass charmin plug. Basically just grabbed some of the insulation from our ceiling and stuffed it as tightly as possible into the neck of a funnel. Takes a while to filter through, but you get most of the Gold out and your Sulfuric can be stored ready for the next batch.

I then just dropped the fibreglass plug straight into some HCl in a beaker and proceeded with regular AR refining.

 

[nickjam]

One week later and I can see through the murky solution. Apparently it is just a slow process that tests ones patience. I am sure a little heat would speed it up, but I want to see how long it takes without heat. Worth it though Sulfuric Acid is not cheap!!!