Dropping gold with H2O2

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Alentia

Alentia

Well-known member
Joined
Oct 8, 2010
Messages
242
Location
Richmond Hill, ON
Not sure if it was discussed on the forum before. My search did not yield good results...

Here is from "unusual chemistry"... Did anyone try it?

"An interesting way to reduce gold(III) chloride back to elemental gold is to use an alkaline solution of hydrogen peroxide. Although usually oxidizer, in some reactions H2O2 can act as a reducing agent.

(2)AuCl4[-] + (3)H2O2 + (6)OH[-] --> (2)Au + (8)Cl[-] + (6)H2O + (3)O2
"
 
I would swear i have heard that mentioned in a youtube video on making white gold. They also call it ormus which is slang for alchemy.
 
From what I understand H2O2 can be an oxidizer or reducer, I thought pH was the key, but I am not sure about that, I know sodium hydroxide and hydrogen peroxide work good to reduce silver chloride to metal, but I have not tried gold.I have read it would though.

I assumed it was similar how water could act as an acid or a base.
 
Hydrogen is in the Electromotive list just above copper, so I've always wondered if some how you could use it to precipitate gold or other pm's from solution.
 
What I do not understand, how do you get OH? Or is it assumed any Hydroxide Salt will release OH in water, like NaOH?

At the end should we get NaCl in the solution rather then free Cl? I will try it and see if it works.
 
I think the gold would need to be fairly pure as other metals would reduce,
I tried to find out more about this, I did find a little, some modern expierimenting in nano technology, and gold and gold palladium catalyst (looked like expieriments to make H2O2), some discussions on the same formula you posted.
I will post some notes I made, maybe you can makes sense of them, they are a jumble:

From wikipedia:
Aqueous solutions of AuCl3 react with aqueous base such as sodium hydroxide to form a precipitate of Au(OH)3, which will dissolve in excess NaOH to form sodium aurate (NaAuO2). If gently heated, Au(OH)3 decomposes to gold(III) oxide, Au2O3, and then to gold metal.



http://chemistry.proteincrystallography.org/article148.html

In certain reactions hydrogen peroxide appears to function as a reducing agent. Thenard (1819) found that gold and silver oxides are reduced by it to the metals: H2O2 + Ag2O = H2O +O2 2 Ag.

Expt. 5. - Add caustic soda solution to a solution of silver nitrate: a brown precipitate of silver oxide is formed: 2AgNO3 + 2NaOH = Ag2O + 2NaNO3 + H2O. Add H2O2 to this: it is at once converted into black metallic silver, with brisk evolution of oxygen. If a further quantity of H2O2 is added, it is catalytically decomposed by the finely divided silver.

Brodie (1850) showed that when hydrogen peroxide acts as a reducing agent, the labile oxygen atom withdraws another oxygen atom from the compound reduced, to produce a molecule of gaseous oxygen. It reacts (rather slowly) with ozone.


Hydrogen peroxide is used as an antichlor to remove excess of chlorine from bleached fabrics:
O2 H2O = O2 + O2 + H2O.Cl2 + H2O2 = 2HCl + O2.

(2)AuCl4[-] + (3)H2O2 + (6)OH[-] --> (2)Au + (8)Cl[-] + (6)H2O + (3)O2


https://sites.google.com/site/unusualchemistry/aqua-regia

http://www.sciencemadness.org/talk/viewthread.php?tid=21266

Not related much but a good find:
http://karin.fq.uh.cu/~cnv1/qf/e_books/HandbookChemPhys2007/handbook/pdf/08_08_86.pdf

http://miningeducation.blogspot.com/2011/12/aqua-regia.html
2HAuCl 4 + 2NaHSO3 = 2Au + 4HCl + Na2 SO4 + SO2
or with the addition of hydrogen peroxide (H2O2) and Sodium Hydroxide (NaOH).

One thing I find funny here, all of the formula's look the same, to me this implies they may have came from the same source.
 
i did this dropping a few times----the gold precipitated is a very pure yellow colour-----i stopped doing it because the reaction becomes violent(almost boil over) and i was afraid to lose some gold powder(spit out)-----------------------
i read now that this method reduces agcl to ag---i will try to do this because i have a lot of agcl from my work

regards to all
Arthur
 
Arthur,

Can you possibly describe the process in details and steps. I would not afraid of boiling too much as I precipitate in sealed vessels.
 
H2O itself should also do it according to the electrochemical chart. Guess you would need quite a lot of it. It also would raise the ph ny dilution, which makes it even easier for the metal to be dropped.
 
Alentia,as far as i remember---to the gold chloride solution i added naoh to ph around 7,then i added h2o2(30 volumes) drop by drop and stirred the solution until a strong reaction took place----the reaction takes place during one or two minutes---after that,you just filter out the gold-----the end


Arthur

Alentia,do not do this in a closed vessel----the gas formed raises the pressure and might explode the vessel
regards
Arthur
 
Thank you, Arthur!

I missed the word "vacuum" in front of the sealed vessel and vacuum is created by scrubber.

What concentration of H2O2 you were using?
 
In fact you get gold oxide, however what I call
the molecular heating decomposes it to gold
and oxygen. (Normally that would happen at
250C). Gold and silver when first formed
adsorb dissociatively H2O2 with a reaction heat
of about 52 kcal/mol
http://www.facebook.com/pages/Gold-electronic-enigma/162208933810735
 
I believe the patent for DBC (aka BDG, dibutyl carbitol) mentions using hydrogen peroxide to precipitate the gold. If it's not the patent, then it is in another text on DBC that I found years ago.

Steve
 
So everyone can comprehend,I pulverize gold ore into powder, than I roast it and run a strong magnet and a weak magnet through it. I dont pan down to consontrate because the gold in the ore is too small (flour gold) . I put the powdered ore into a 5 gal bucket and add 3 to 1 hydrochloric >bleach. Let that sit with a lid on( with a hole in it to vent, otherwise pressure to ba boom) for a couple of days while mixing a couple times a day. Than I filter the solution into 1 gallon jars and let sit in the sun for a day or two. Than I pour hydrogen peroxide (about a cup) in the solution and decant the next day. Put the mud in a pyrex dish and heat on a hot plate for a couple of hours and Bam. I have gold powder that I mix with borax and heat with a toarch until Gold showes up.
 
Alentia said:
Not sure if it was discussed on the forum before. My search did not yield good results...

Here is from "unusual chemistry"... Did anyone try it?

"An interesting way to reduce gold(III) chloride back to elemental gold is to use an alkaline solution of hydrogen peroxide. Although usually oxidizer, in some reactions H2O2 can act as a reducing agent.

(2)AuCl4[-] + (3)H2O2 + (6)OH[-] --> (2)Au + (8)Cl[-] + (6)H2O + (3)O2
"
Click to expand...
Theoretically, peroxide can precipitate gold in a pure alkaline solution if there is no clarification about the presence of other metals.
But in practice, this will only work for pure tetrachloroaurate solution with pH < 9. AuCl4[-] doesn't exist in solution when pH > 9.5 (see Au-H2O-Cl Pourbaix diagram).
 
Sonofman said:
So everyone can comprehend,I pulverize gold ore into powder, than I roast it and run a strong magnet and a weak magnet through it. I dont pan down to consontrate because the gold in the ore is too small (flour gold) . I put the powdered ore into a 5 gal bucket and add 3 to 1 hydrochloric >bleach. Let that sit with a lid on( with a hole in it to vent, otherwise pressure to ba boom) for a couple of days while mixing a couple times a day. Than I filter the solution into 1 gallon jars and let sit in the sun for a day or two. Than I pour hydrogen peroxide (about a cup) in the solution and decant the next day. Put the mud in a pyrex dish and heat on a hot plate for a couple of hours and Bam. I have gold powder that I mix with borax and heat with a toarch until Gold showes up.
Click to expand...
Welcome to the forum.
Interesting process.
Do you test if you got all the gold out of solution after adding H2O2?
How pure is your gold with this process?
 
Sonofman said:
So everyone can comprehend,I pulverize gold ore into powder, than I roast it and run a strong magnet and a weak magnet through it. I dont pan down to consontrate because the gold in the ore is too small (flour gold) . I put the powdered ore into a 5 gal bucket and add 3 to 1 hydrochloric >bleach. Let that sit with a lid on( with a hole in it to vent, otherwise pressure to ba boom) for a couple of days while mixing a couple times a day. Than I filter the solution into 1 gallon jars and let sit in the sun for a day or two. Than I pour hydrogen peroxide (about a cup) in the solution and decant the next day. Put the mud in a pyrex dish and heat on a hot plate for a couple of hours and Bam. I have gold powder that I mix with borax and heat with a toarch until Gold showes up.
Click to expand...
This is strange behaviour. If you used regular 30 % HCl, the solution will be still pretty acidic. And in acidic solutions, peroxide is very strong oxidant and it dissolve gold due to formation of chlorine in the solution.
I personally do the opposite - I use HCl and peroxide to dissolve gold powder, and it is doing extraordinary work. In acidic enviroment, peroxide release chlorine, which is the active oxidizer for gold.

Maybe your ore is basic, meaning you will neutralize the solution eventually and spent the HCL, lowering the pH and allowing some gold hydroxide or other compound to precipitate.
Otherwise I do not see this working.
 

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