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Author: Subject: Red solution from gold processing, WTF is it ?
Sulaiman
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[*] posted on 10-7-2018 at 04:32
Red solution from gold processing, WTF is it ?


I dissolved gold jewelry and e-scrap in aqua regia, expecting about 2+ g pure Au total.
I used too much nitric acid so when trying to drop the gold I had to use a lot of sodium metabisulphite,
one of the additions was too much and foaming caused the contents to overflow slightly.

What I do not understand is why I have sediment in a RED solution


WTF.jpg - 1.5MB

Before adding SMB the solution was green with a tinge of gold/yellow.
I have done gold scrap + aqua regia + SMB four or five times before and never seen this colour.

Anyone guess what causes the red solution ?
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HeYBrO
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[*] posted on 10-7-2018 at 04:43


My guess is colloidal gold
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j_sum1
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[*] posted on 10-7-2018 at 04:50


That's my guess also. It is pretty cool.
You can actually get different shades if you can change the particle size.
I would ampoule some for the element collection.

There is not much gold there but if you dilute it sufficiently, bottle it up, label it as Ormus Gold and sell it to New Age types, it is worth a fortune.
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XeonTheMGPony
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[*] posted on 10-7-2018 at 05:11


Quote: Originally posted by j_sum1  
That's my guess also. It is pretty cool.
You can actually get different shades if you can change the particle size.
I would ampoule some for the element collection.

There is not much gold there but if you dilute it sufficiently, bottle it up, label it as Ormus Gold and sell it to New Age types, it is worth a fortune.


About the only good the new age types are good for is selling overpriced air too lol, look up "Energized" water lmao
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woelen
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[*] posted on 10-7-2018 at 05:18


It may also be palladium. Palladium ions have this very typical brown/red color.
I hardly can believe it is colloidal gold:
1) Colloidal gold has amuch brighter color, more like pink/red instead of brown/red.
2) In the strongly salted solution you have here, colloidal gold quickly would precipitate, giving a dirty brown paste of very finely divided impure gold.

What is the source of your gold? This also may give a clue of whether it may contain palladium or not.




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Sulaiman
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[*] posted on 10-7-2018 at 05:28
If it is colloidal gold ...


I just tested the red liquid with SnCl2 and got no reaction,
so I assume that most of the gold is in the precipitate and some in colloidal suspension.

1) how to separate the colloidal gold from the (presumed still) dissolved copper etc. ?

2) can an excess of SMB/SO2 drop copper out of solution, even temporarily/transiently/ephemerally ?
I ask because as I was adding SMB to the gold-bearing solution,
what looked like fine copper powder appeared in the froth, then dissolved away.
I have seen gold powder/sand look similar, and there was still probably some nitric acid in solution at that stage.

... (why red ? I'd expect a lot of green copper ions to remain in solution)



In my previous attempts at anti-bacterial colloidal silver synthesis I found that above about 25 ppm the colloidal particles eventually settle out as a precipitate, so if this is colloidal gold, then as suggested I doubt that there is a significant quantity of gold in suspension.
IF I can get just the colloidal gold without the contaminants then I may try selling some via eBay, just for fun :D


EDIT:
@woelen the starting material was;
. a little gold plated electronics scrap, common stuff I've refined before
. 7.37g jewellery, various bits of cheap scrap jewellery from my family and a friend: chains, rings, earrings etc. mostly .375 or plated.

In my waste bottle (from the initial nitric acid wash/soak) I see two green coloured liquid layers, one like copper, one like nickel, and precipitate/crud at the bottom.

This is becoming much more interesting than just getting a sample of gold :D

#################################################
On dilution the red liquid became yellow (slightly green) and did not react to SnCl2 (even after a little aqua regia added) or excess SMB so I discarded it.
Whatever the red liquid was, I can not determine now.
Nett = 2.06g Au and a bottle of corrosive toxic waste & a mystery.

[Edited on 10-7-2018 by Sulaiman]
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diddi
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[*] posted on 10-7-2018 at 17:22


did you digest any other components in your ewaste. eg tiny surface mounted capacitors. they have Pd. i have had that sort of colour from monolithic surface mount capacitors



Beginning construction of periodic table display
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Sulaiman
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[*] posted on 11-7-2018 at 07:19


No palladium bearing components electronic components that I noticed,
but possibly Pd used to plate earrings ?

In any case, dilution changed the red/brown solution to yellow,
no amount of SMB/SO2 added produced any precipitate or visible change.
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MrHomeScientist
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[*] posted on 11-7-2018 at 08:13


Out of curiosity, how did you "discard" your "corrosive toxic waste"?
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Sulaiman
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[*] posted on 11-7-2018 at 13:34


I have not decided yet,
it consists of about 200ml and it is in a bottle waiting for me to decide its fate.

The 'corrosive' part is easy to neutralise,
the toxic part is because I expected some lead and nickel.

Sulphuric acid produced no precipitate indicating no lead,
but there could have been enough nitric acid to keep any lead oxidised so I'm not certain.
I doubt that I will try to recover anything from the waste so the metals will end up in landfill as sulphates.


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