Na2S2O3 as a gold precipitant?
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Irons
Well-known member
If they have, they probably won't admit it. :mrgreen:
Sodium thiosulfate is one component of an alternative lixiviant to cyanide for extraction of gold.[3] It forms a strong complex with gold(I) ions, [Au(S2O3)2]3-. The advantage of this approach is that thiosulfate is essentially non-toxic and that ore types that are refractory to gold cyanidation (e.g. carbonaceous or Carlin type ores) can be leached by thiosulfate. Some problems with this alternative process include the high consumption of thiosulfate, and the lack of a suitable recovery technique, since [Au(S2O3)2]3- does not adsorb to activated carbon, which is the standard technique used in gold cyanidation to separate the gold complex from the ore slurry.
http://en.wikipedia.org/wiki/Sodium_thiosulfate
Sodium thiosulfate is one component of an alternative lixiviant to cyanide for extraction of gold.[3] It forms a strong complex with gold(I) ions, [Au(S2O3)2]3-. The advantage of this approach is that thiosulfate is essentially non-toxic and that ore types that are refractory to gold cyanidation (e.g. carbonaceous or Carlin type ores) can be leached by thiosulfate. Some problems with this alternative process include the high consumption of thiosulfate, and the lack of a suitable recovery technique, since [Au(S2O3)2]3- does not adsorb to activated carbon, which is the standard technique used in gold cyanidation to separate the gold complex from the ore slurry.
http://en.wikipedia.org/wiki/Sodium_thiosulfate
lowg
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Irons said:
Since I had problems getting SMB, I tried this stuff that I got from some communist lab. that is down for about 45 years. :lol:
Nice looking AuCl3, when I added Na2S2O3 precipitated gold into brown form, then turned in red/orange, then the whole solution turned red/orange, when I filtered it became brown again, then dried - and it became solid as rock. And very hardly dissolved in AR.
I hope I'll get some SMB tomorrow
Thank you very much for your reply!
Irons
Well-known member
SO2 gas will work as well. If you can find some sulfur, burning it will produce SO2. Bubbling it into the solution of AuCl3 will precipitate the Au.
It's not the best way to go, but if you're in a situation where chemicals are difficult to acquire, it will do the job.
You can make SMB by bubbling SO2 gas into Sodium Hydroxide solution.
It's not the best way to go, but if you're in a situation where chemicals are difficult to acquire, it will do the job.
You can make SMB by bubbling SO2 gas into Sodium Hydroxide solution.
dtectr
Well-known member
On lazersteve's website read the document/patent (sorry I don't remember which it is ) on sulforous acid. I believe, at 2 a.m. :lol: that its a process for producing SO2 gas for precipitation. After I get some sleep, I'll recheck & edit this, if necessary.
) on sulforous acid. I believe, at 2 a.m. :lol: that its a process for producing SO2 gas for precipitation. After I get some sleep, I'll recheck & edit this, if necessary.Ferrous sulfate will precipitate gold, you can make it with 10% sulfuric acid and pure soft iron (old transformer laminate cut to pieces, little heat or time.
lowg
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dtectr said:On lazersteve's website read the document/patent (sorry I don't remember which it is
Thank you! It is ok by now.
lowg
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Well.. Today I bought Na2S2O5.
And the sales-guy (some old chemist professor) offered me to try Na2S2O7. for 2$, 1kg and I took it.
Do you think I am being ripped off? 8)
If so
Maybe I could find a good use for it. OR maybe I am just totally ripped off.. :roll:
And the sales-guy (some old chemist professor) offered me to try Na2S2O7. for 2$, 1kg and I took it.
Do you think I am being ripped off? 8)
If so
Maybe I could find a good use for it. OR maybe I am just totally ripped off.. :roll:
A
Anonymous
Guest
Straight SMB,Good Job.How much did you pay?lowg said:
I do not suggest using it.Sodium pyrosulfate tends to drag down contaminants upon precipitation,giving you "dirty"gold powder that should be redisolved.lowg said:
Almost the same as Super Iron Out.lowg said:
A
Anonymous
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http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=6763&p=68712&hilit=super+iron+out#p65145
eugene-bright
Member
The paper mentions traditional one-step reduction of HAuCl4 by sodium thiosulfate.
Probable stoichiometry: 2AuCl3 + Na2S2O3 + 3H2O → Na2SO4 + 6HCl + 2Au + SO2.
The problem is caused by Cu2+ presence: 2CuCl2 + 2Na2S2O3 + 2H2O → Cu2S + S + 4NaCl + 2H2SO4.
One can get rig of CuS and S by washing precipitate in the concentrated HNO3.
I strongly suggest using crystalline NaCl instead of HCl for aqua regia preparation. Also the addition of NaClO is advised to speed up the reaction advent.
Probable stoichiometry: 2AuCl3 + Na2S2O3 + 3H2O → Na2SO4 + 6HCl + 2Au + SO2.
The problem is caused by Cu2+ presence: 2CuCl2 + 2Na2S2O3 + 2H2O → Cu2S + S + 4NaCl + 2H2SO4.
One can get rig of CuS and S by washing precipitate in the concentrated HNO3.
I strongly suggest using crystalline NaCl instead of HCl for aqua regia preparation. Also the addition of NaClO is advised to speed up the reaction advent.
eugene-bright
Member
Other fallback gold reducing precipitation methods:
- Metals like Zinc, Aluminum and Magnesium.
- Ascorbic Acid.
- Hydrogen from vigorous electrolysis.
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Much better use Copper since it will drop only the precious metals unlike the one you mention that will drop practically all metals.
You are forgetting Sodium MetaBisulfite SMB, Ferrous Sulfate, Oxalic acid and more.
Hydrogen from electrolysis, I have never heard about that and is it the Hydrogen or the ions transfer in the electrolysis doing the job?
eugene-bright
Member
In this crazy video I observe strong anodic reaction, though I expected the gold being recovered on the cathode. It looks more like that the gold is being reduced by the anode material itself, otherwise it doesn't make sense for me.
Of course it will, it is called cementing.
The same process as Zinc, Aluminum and so on.
No need for electrolysis.
And the only viable way if the solution is not clean (pure Gold) is Copper.
eugene-bright
Member
That's interesting. In my case I got no gold in precipitate after attempting the cementing with thiosulfate. Probably in the presence of HNO3 the favorable reaction yields soluble gold thiosulfate. Bad luck.
If I remember correct one of the reasons Thiosulfate is not used much, is that it really do not want to let the Gold go.
It seem very hard to precipitate the Gold. so resins are usually used.
What do you mean with Cementing with ThioSulfate?
It is a solvent/leaching agent for Gold is it not?
Not a precipitant?
