Au Positive Solution -> SMB -> Pt Positive Solution: what?

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ZiegenSauger

Well-known member
Joined
May 18, 2020
Messages
73
Friends, Merry Xmas everybody!!!! Are my assumptions correct?

I have accumulated under 200g of black powder from incinerating whatever is left from recovering Sterling Silver and Silver Plated items.
First I processed with HNO3, resulting solution processed with 99% Cu stripes and a very funny sand silver dropped (interesting actually, does not look like cement silver like it usually is from the main processing, it is like ground shiny metallic silver).
Remaining solids were washed until clean liquid would come down.
Then processed with AR resulting a greying green goo solution.
Filtered, the most beautiful crystalline dissolved gold type solution came down. No excess nitric whatsoever.
Poured SMB, solution became darker cloudy, I did not see precipitants (could have been very little).
Stannous test now positive for Pt (see picture below):
2020-12-23 17.38.36.jpg
Test to the right was taken over 6hrs before photo, so it was even darker than now.
Test to the left was just made 10 before photo.

I think I am on the verge of topping mistakes over mistakes: I added NaOH, solution seemed to start reacting but nothing. Set aside to rest overnight.
Filtered.
I added Cu stripes to the Stannous positive solution for Pt and set it aside.

Filtered residues will go to A/R again to try to recover Au.

Any comment or recommendation or advice?

THANK YOU
 
Friends,

I filter the Pt pregnant solution in one 2L beaker and added 99% Cu stripes. Very little happen this far, if any. Remainder 1L I added to another beaker with Zinc, black precipitate is coming out: wonder whether Zinc reacts faster and yields elemental Pt or this is pure contamination - will let Cu for a week to see what happens.

For the Au, filtered solids are back to AR with immediate crystal Au solution. I am cooking for a few hrs to make sure everything goes in solution. This time I will drop with 99% just in case.

Any comment is much appreciated.
 
I am not sure that the reddish color on the lower q-tip is Pt. The color appears similar to the way the reaction might look when there is extra SMB in the solution.

However, when it doubt, cement it out. It appears that is what you are doing at this point, so you should be good to go.
 
Nether one of those tests show any sign of Pt !!! --- (or any other PGM)

Colors of a stannous test -------------

Gold - purple to black with a purple tint to the black if the concentration of the gold in solution is HIGH (when black the purple tint will be evident at the edges of the test

Palladium - depending on concentration - a deep but also bright green (think forest green or emerald green) at lower concentration to almost black with a green tint to the black at HIGH concentration (again - when black the green will be evident at the edges of the test) --- sometimes (depending on base metals in solution) you may get a light green test (think a lime green) that is likely "not" Pd

Platinum - a BRIGHT orange to deep bright orange to a dark reddish orange & even a black/reddish orange

These colors are "very" distinct & vibrant - & you will never mistake them - once you see those test made with solutions made with each of those PURE metals

Brown --- or brownish orange is "often" the result of using to much SMB - but can also be a result of iron oxide (actual iron/rust particles) in your solution --- this is known as a "false" positive test --- and that is what you are seeing in the pic of the test you posted - its "not" a nice bright orange - it's brown(ish)

one more thing about stannous testing - if there is silver in the solution - the stannous test can result in a blueish/grey (kind of purplish) known as "photo" grey - that is the result of the stannous forming silver chloride which then turns the purplish blue/grey when exposed to light (which happens quickly) & again that is what your test looks like to me (though I could be wrong) it just doesn't look like a true purple for gold but more like the photo grey of silver chloride

Kurt
 
Thank you very much Kurt and deedigity, this helps a lot.
New information I did not have before, apprrciate helping my learning.

I diluted and split in 3 beakers, all beakers have the apparent photo silver now.

Interesting piece is the source material for this did not dilute in nitric. From the source in nitric, I recovered ~100g of pure Silver, remaining residues - after quadruple washing - i dissolved in AR with a crystal mustard yellow filtered solution. But no precipitant works, only NaOH drops me something that takes me to same vicious cycle.

I am clearly chasing my tail. Dissolved Ag only gets in a green or blue solution because of Cu for example. I dont have Cu at all, so the psychologic when sees the yellowish solution would immediately assume anything but Ag.

I have 2L with Cu stripes and 1.5L with Zinc stripes. Both of them are dropping something. I will wait a few days, filter and reprocess with the Ag mindset now.

I also have 250mL of what I thought was pure Au dropped with SMB and NaOH. With the new learning I will have to think what to do with that liquid. Since it has some NaOH not sure if NaCl or HCl will help me drop AgCl at this point.

Summary, what a mess!!! Big big big thank you for taking your time to reply.

Merry Xmas and a Wonderful new year.

America uber alles!!!!!
 
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