# Purifying nuggets, fine gold, flakes, etc....



## NuggetHuntingFool (Jan 21, 2008)

Hello,


Let's say that I went panning and found nuggets, small gold, flakes, etc....



What would I have to do to purify those?


Do I simply melt and the impurities will leave or float on top??


Or, is gold pretty much pure in its natural state. Assuming it came from stream/river beds and not quartz veins.


Thanks a lot!


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## Harold_V (Jan 22, 2008)

While gold has been found 999 quality in nature, it is highly unlikely you have such gold. Typical placer gold is alloyed with silver, and often copper. 

Melting placer gold will separate it from the black sands and non-metallic materials, but melting alone does little to improve the quality of the gold. In order to remove the traces of base metal or silver, the gold should be dissolved with aqua regia and selectively precipitated. That alone can be troublesome in that gold that contains too much silver is difficult to dissolve in aqua regia. Fine bits of gold will usually dissolve completely before action ceases due to the formation of silver chloride, but larger pieces often need to be inquarted, then parted, removing the base metals and silver, leaving behind gold in a high state of purity, and finely divided, ready to be dissolved for the final refining process. 

It's a little more involved than the Reader's Digest version I just presented, but it should serve to give you a sense of direction. Melting alone will not purify your gold----once combined, most metallic elements will not stratify when melted.

Harold


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## NuggetHuntingFool (Jan 22, 2008)

Nice.


Thanks


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## usaman65 (Jan 22, 2008)

where the gold came from is a big tip 

if it is from australia it usually is 22-23kt if it is from alaska it tends to be .750 or 18k

you can find out the purity of your niggets by looking on google etc. about the place they are from.....

kev


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## ChucknC (Jan 22, 2008)

Please remember, nuggets and specimens can be worth far more in the natural state than refined into a prill or bar. Check out the prices for 1/4oz and larger nuggets and you'll see what I mean. 8) Don't ruin a potentially valuable prospect by trying to refine the nugget or specimen. I know a couple of people who got a couple of hundred dollars for their refined gold who later found out the pieces would have brought several thousand dollars if left alone.  

Fines would be worth processing. Just remember, like Harold said, silver, copper, or even platinum group metals are the main alloys of gold found in nature. Sometimes the impurities are worth more than the gold.  I know a place in the NC mountains where the main impurity in the gold seems to be Pt.  8) You should have seen that frosted soccor ball of a prill from the fire assay. Sweet.

Even in processing the fines, remember the law of diminishing returns. It is only economically possible to get the gold just so fine. After that, it's either imposiible to do with your equipment, or more expensive than it's worth.  

Chuck


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## Richard36 (Feb 2, 2010)

If I were to do this, 
I would first dissolve the Gold in Aqua Regia. 
Then neutralize the AR with Urea, or remove the nitric portion by the boil down method.

(Boil the AR down to 1/3 volume of solution, add Hydrochloric Acid or the weaker, more common form called Muriatic Acid, until the original starting volume of solution is achieved, then boil down again to 1/3 of its volume. Repeat this procedure three times to expel the Nitric portion of the Aqua Regia.) 

After the Aqua Regia has been boiled down three times,
(Add distilled water to the boiled down solution until it equals the original volume) 
Or Urea added until it no longer fizzes, and is neutralized, 
Then add Sodium MetaBisulfite in an amount equal to, 
Or slightly greater than the weight of the Gold expected to be recovered. 

This will drop the Gold as a brown powder precipitate. 
Filter the solution to recover this powder, and let it dry.

(Boiling the Brown Gold Precipitate in distilled water will help to remove impurities from it. Let solution settle after boiling, pour off the bulk of solution, then filter the remaining portion with the precipitate. After filtering, rinse the precipitate and filter with distilled water while it is still in a plastic funnel, then let dry.) 

This powder can then be mixed 1 part Gold Precipitate to 3 Parts Borax, 
Then melted to produce a reasonably pure Gold Button.

This Gold button could then, but doesn't have to, be Fire Refined in a Furnace with the following flux Formula. 
This Formula is for material that is at least 70% Gold, and will slag off Silver, Iron, Copper, and other contaminants. 
Use 1 Part Flux to 3 to 5 Parts Gold. 
It was designed for Fire Refining Placer Gold, without the Aqua Regia process as a preliminary step, 
but the AR process is an excellent step to take first.

3 parts Sodium Carbonate. (Soda Ash)
1/2 part Borax. 
1 part Silica.
1 part Manganese Dioxide.

Optional:
1/2 part Lime-Fluorspar Mixture.

Lime-Fluorspar Mix.
1 part Fluorspar. (CaF2, Calcium Fluoride)
1 part Calcium Oxide. (CaO, Lime, Type S, Unslaked)

I hope that this has been Helpful.

Sincerly; Rick. "The Rock Man".


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## Irons (Feb 2, 2010)

I would not use Urea in solutions containing PGMs.


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## Richard36 (Feb 2, 2010)

Irons said:


> I would not use Urea in solutions containing PGMs.



Fair enough.

What are the problems that Urea causes in solutions containing PGM's?
I have not done much with the PT group other than testing ores for their presence.

Sincerely; Rick. "The Rock Man".


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## Irons (Feb 2, 2010)

Richard36 said:


> Irons said:
> 
> 
> > I would not use Urea in solutions containing PGMs.
> ...



PGMs have an affinity for Ammonia and amines. Urea meets that criteria. It may cause you problems recovering the PGMs.


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## Richard36 (Feb 2, 2010)

Irons said:


> Richard36 said:
> 
> 
> > Irons said:
> ...



So the boil down method would be best, if the gold does, or is suspected of containing PGM's.
Am I correct?

Sincerely; Rick. "The Rock Man".


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## Irons (Feb 2, 2010)

Richard36 said:


> Irons said:
> 
> 
> > Richard36 said:
> ...



The boil-down method is the one of choice, regardless. I guess if you're in a hurry, Urea will work, but it adds another variable to the mix.


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## Oz (Feb 2, 2010)

You can also just skip the nitric and use HCl and Cl2 gas. Chlorine is easier to eliminate than nitric.


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## Richard36 (Feb 2, 2010)

Oz said:


> You can also just skip the nitric and use HCl and Cl2 gas. Chlorine is easier to eliminate than nitric.


 
I have never tried this method.
Oz, could you explain this, for my benefit, and others?



Irons said:


> Richard36 said:
> 
> 
> > Irons said:
> ...



Thanks Irons.

Sincerely; Rick. "The Rock Man".


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## Oz (Feb 2, 2010)

It is nothing that hasn't been covered extensively here before. It is my preferred method for most things that others use AR on, I save my nitric for silver. There are many ways to introduce the chlorine gas, most here just add sodium hypochlorite (unscented bleach) to their HCl.


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## Richard36 (Feb 2, 2010)

Oz said:


> It is nothing that hasn't been covered extensively here before. It is my preferred method for most things that others use AR on, I save my nitric for silver. There are many ways to introduce the chlorine gas, most here just add sodium hypochlorite (unscented bleach) to their HCl.


 
Fair enough.

That provided a direction for others to research, (The Acid/Clorox Method.) and that was my primary objective.
You did a pretty good job of describing the process to me over the phone awhile back.
I appreciate that. 

Thanks Oz.

Sincerely; Rick. "The Rock Man".


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## Oz (Feb 2, 2010)

I am glad to help but I am not a typist. I can cover in 5 minutes on the phone that would take an hour or more to write. 

Feel free to call me anytime Rick.


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## Richard36 (Feb 2, 2010)

Oz said:


> I am glad to help but I am not a typist. I can cover in 5 minutes on the phone that would take an hour or more to write.
> 
> Feel free to call me anytime Rick.



lol! 

I know the feeling. 
I do not type all that fast either.

Thanks for the invite to call.
I hope that you know this invitation goes both ways.
My phone # is in my signature.

Feel free to give me a call if you have any questions, or would like to chat.

Thanks again Oz.

Sincerely; Rick. "The Rock Man".


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## Anonymous (Mar 24, 2010)

i'm new to this but i would like to know how to purify gold in jewlery form?


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## jimdoc (Mar 24, 2010)

You can start by reading on the forum, its all right here already.
Look for the forum handbook and Lazersteves videos.

Jim


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## Anonymous (Mar 24, 2010)

good looking out buddy, may i ask where this info's at? i don't know how to get around this sit.


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## jimdoc (Mar 24, 2010)

Check the bottom of these member's page info for links;
http://goldrefiningforum.com/phpBB3/memberlist.php?mode=viewprofile&u=8

http://goldrefiningforum.com/phpBB3/memberlist.php?mode=viewprofile&u=1666


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## Richard36 (Mar 24, 2010)

obert101 said:


> i'm new to this but i would like to know how to purify gold in jewlery form?



The process that I posted earlier in this thread will work on jewelry, (Commonly called Karat Gold), as well as placer Gold.


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## Harold_V (Mar 24, 2010)

obert101 said:


> i'm new to this but i would like to know how to purify gold in jewlery form?


The most valuable tip I, or anyone, can give you is to *read Hoke*. When you understand what she teaches, you can process values you are likely to encounter in any shape or form. 

Harold


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## cory123 (May 26, 2011)

by using only the minimal amount of nitric, after boiling, adding hydrochloric, and more boiling, and then diluting with water before adding smb , there should be no nitric if youve used an amount of 1 ml per gram of gold. does anyone agree


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## fireengineer2004 (May 29, 2011)

From everything I've read, placer gold is purer than hard rock gold, and any placer gold, picker size or larger is worth a premium over spot. I personally wouldn't melt anything other than fine or flour gold.


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## sawmill (May 29, 2011)

Placer gold is just hardrock or vein gold that has
eroded from a vein in hardrock. It is no purer than
its source. The purity of placer gold is another old
myth . 
Placer gold can be a little cleaner ,to process
than vein gold,because it is free of most of the
oxides ,and other nasties ,because of the erosion
process. The gold content will still be the same as
the vein source,so will the silver ,copper and other
metal content.


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## Cody Reeder (May 31, 2011)

I wonder how the Egyptians purified their gold. its pretty hard to find pure gold in nature but on all those museum documentaries they say that the gold masks and stuff where pure gold. Are they saying that its "pure" and only contains native gold? Or did the Egyptians really have a way of refining the gold?


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## Harold_V (May 31, 2011)

A roasting process was used. Silver was converted to silver chloride, which was then rinsed from the gold. You may be able to find more by doing a search. What I mentioned I recall from reading many years ago. My aging mind may not remember things correctly. 

Purity is a matter of degree. Highly unlikely they achieved a level of purity in keeping with today's technology, but they had very little to work with. I'd say they were masters of the art. 

Anyone see the Ramses II display when it toured the US about 25 years ago? Some of the finest goldsmith work you can imagine--all done, what, 4,000 years ago?

Boggles the mind.

Harold


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## Reno Chris (May 31, 2011)

The ancient Colombian goldsmiths of the new world learned a different "purification" trick - they added considerable copper to their gold - diluting it out so much that the alloy appeared very coppery red. They then cast their sacred objects and treated them with naturally acidic materials which in combination with the oxygen from the atmosphere ate away the copper but not the gold, leaving what was essentially a gold plated surface created by subtraction of the copper. It allowed many more "gold" objects to be cast!


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## goldsilverpro (May 31, 2011)

Reno Chris said:


> The ancient Colombian goldsmiths of the new world learned a different "purification" trick - they added considerable copper to their gold - diluting it out so much that the alloy appeared very coppery red. They then cast their sacred objects and treated them with naturally acidic materials which in combination with the oxygen from the atmosphere ate away the copper but not the gold, leaving what was essentially a gold plated surface created by subtraction of the copper. It allowed many more "gold" objects to be cast!



The modern term for this is "Depletion Gilding". Interesting topic. Excellent article.


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