Okay, I'm here to admit defeat and see if I can get a little help.
I tried a test batch of about 1 lbs of tightly trimmed fingers a few weeks ago. Everything went more or less to plan, dissolving the gold in AR, careful not to add too much Nitric Acid, precipitate, and (eventually) melt. I didn't have any Stannous though to test and make sure I wasn't leaving any gold behind, a rookie mistake I've learned since my yield was only 1.25g or about 50% what I expected (actually expected around 1.75 - 2 g for beginner inefficiencies).
Luckily, I saved my waste wash and left over solution after precipitating.
Fast forward to a few days ago. I dropped a few drops of Stannous into the solution as is (basically about 700 ml of previous AR and distilled H2O). Nothing. Frustrated I made a rookie mistake and squirted a bunch more Stannous into the solution (maybe 15 ml), but still nothing. Next morning though, the solution is dark and there's mud on the bottom. Okay, I know Stannous works by being a precipitant, so I guess the stannous precipitated the gold in solution.
Yes, I know the stannous would also contaminate it with tin, thus not ideal.
So my plan going forward was to evaporate off the excess, and kind of start from scratch, with washing the powder with HCL a few times to hopefully remove the tin, then re-AR the batch, filter, precipitate, and go from there.
Here's where I'm stuck...last night I was slowly evaporating the solution (not boiling). After a while, I checked and all the precipitated mud was gone and the solution was now yellow (with a green tint). Best I could guess is somehow evaporating created contaminated Auric Chloride somehow. I let it cool over night, and the solution stayed in the heated form.
Okay, I can maybe deal with that. I filtered the garbage off again (bits of board, etc) and figured I'd precipitate the (hopefully) gold off and go back to my original plan.....except no matter how much SMB I put into solution (fizzing and reacting nicely), it doesn't release the gold. It's still yellow but a little cloudy now (not good cloudy).
I'm not sure what my next step is. I'm assuming the tin is causing a problem but I don't know what or what to do. I'm not really concerned for the value in the gold as I am trying to learn and gain experience. I'm open to whatever advice/tips anyone may have.
Thanks
I tried a test batch of about 1 lbs of tightly trimmed fingers a few weeks ago. Everything went more or less to plan, dissolving the gold in AR, careful not to add too much Nitric Acid, precipitate, and (eventually) melt. I didn't have any Stannous though to test and make sure I wasn't leaving any gold behind, a rookie mistake I've learned since my yield was only 1.25g or about 50% what I expected (actually expected around 1.75 - 2 g for beginner inefficiencies).
Luckily, I saved my waste wash and left over solution after precipitating.
Fast forward to a few days ago. I dropped a few drops of Stannous into the solution as is (basically about 700 ml of previous AR and distilled H2O). Nothing. Frustrated I made a rookie mistake and squirted a bunch more Stannous into the solution (maybe 15 ml), but still nothing. Next morning though, the solution is dark and there's mud on the bottom. Okay, I know Stannous works by being a precipitant, so I guess the stannous precipitated the gold in solution.
Yes, I know the stannous would also contaminate it with tin, thus not ideal.
So my plan going forward was to evaporate off the excess, and kind of start from scratch, with washing the powder with HCL a few times to hopefully remove the tin, then re-AR the batch, filter, precipitate, and go from there.
Here's where I'm stuck...last night I was slowly evaporating the solution (not boiling). After a while, I checked and all the precipitated mud was gone and the solution was now yellow (with a green tint). Best I could guess is somehow evaporating created contaminated Auric Chloride somehow. I let it cool over night, and the solution stayed in the heated form.
Okay, I can maybe deal with that. I filtered the garbage off again (bits of board, etc) and figured I'd precipitate the (hopefully) gold off and go back to my original plan.....except no matter how much SMB I put into solution (fizzing and reacting nicely), it doesn't release the gold. It's still yellow but a little cloudy now (not good cloudy).
I'm not sure what my next step is. I'm assuming the tin is causing a problem but I don't know what or what to do. I'm not really concerned for the value in the gold as I am trying to learn and gain experience. I'm open to whatever advice/tips anyone may have.
Thanks