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Removing mercury from gold


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#1 hurthawk

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Posted 22 January 2011 - 02:36 AM

I show the retorting process to remove mercury from gold.

retorting

#2 Ridge Runner

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Posted 22 January 2011 - 04:53 PM

hurthawk
For what it's worth.A & B Prospecting Supplys in Mesa AZ. is the only place that I know of that you can still buy a retort.
Thanks for the V.
Chuck Anders
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#3 DOC

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Posted 23 January 2011 - 01:28 PM

Good video, and I also appreciate the fact that you advise people to stay way clear of the retort while it is working.

Properly used the retort is relatively safe because you are actually capturing almost all vapors, cooling them and returning the vapors to a liquid, via the cooling process.

If you want to preserve your nuggets you can also use Nitric Acid to burn off the Mercury. However this is much more dangerous because you do not recover the Mercury you simply vaporize it and send the vapors off into the atmosphere. I don't know if there is a way to actually capture the vapors when you use Nitric Acid so you could return it to liquid form.

When I was in Sudan, I talk to prospectors there who use Mercury extensively to amalgamate their gold out of black sand and warned them about the hazards involved in using Mercury. They don't understand the serious health hazards involved in using Mercury to amalgamate gold.

I printed an article showing how it was a safer process to eliminate Mercury from the process and to separate gold from black sand by simply using Borax as a flux, and heating the gold to melt it. Gold being heavier drops to the bottom, the black sand forms a crust that is just burned off.

Hopefully some of them will abandon the use of mercury and start using this safer alternative.

Doc
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#4 Huego

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Posted 23 January 2011 - 05:53 PM

Good video, and I also appreciate the fact that you advise people to stay way clear of the retort while it is working.

Properly used the retort is relatively safe because you are actually capturing almost all vapors, cooling them and returning the vapors to a liquid, via the cooling process.

If you want to preserve your nuggets you can also use Nitric Acid to burn off the Mercury. However this is much more dangerous because you do not recover the Mercury you simply vaporize it and send the vapors off into the atmosphere. I don't know if there is a way to actually capture the vapors when you use Nitric Acid so you could return it to liquid form.
...... Doc


I concur with the comment above re the retort being relatively safe for removing & recovering mercury IF used properly. It is dangerous when not used properly.

However, I can't agree that nitric acid ..... "burns off the mercury ..... you vapourise it ...into the atmosphere". Respectfully, that understanding is plain wrong. This is the 'science' (chemistry) behind what happens to those interested.

Nitic acid will effectively dissolve mercury, leaving any gold behind. [Care needs to be taken to not use this acid with any chloride (eg salt or hydrochloric acid) or gold will be lost, ie some will dissolve.]

With this acid, the mercury dssolves, ie goes into solution, as mercuric nitrate (water soluble, but very toxic). It does not vapourise. The brown clouds of toxic gas given off as nitric acid dissolves metals (like mercury, copper etc) is nitrogen dioxide, but it contains no mercury vapour. If one is using this acid care with skin, eye and vapour protection is required. It is best diluted 1 parts with 2 parts of clean water. This reduces the vigor of the reaction. Remember, the mercury (metal) is converted to a toxic acidic liquid above the gold. The mercury can be recovered for re-use with clean zinc swarf.

Huego (Doc 2) B):)
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#5 DOC

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Posted 25 January 2011 - 11:52 PM

Thank you for the clarification. Sometimes I don't exactly remember what I learned. I remembered that it was dangerous to use nitric acid on Mercury, and I thought it was because of the vapors. I didn't realize it actually took the Mercury into solution. Good to know. Whatever the case, at least I remembered it was dangerous!

Sort of like the time I got my beaker of nitric acid confused with my beaker of Muriatic acid.

I took the beaker of muriatic acid, thinking it was the nitric, and added some more nitric to it.

I proceed to drop a 1/2 ounce a 1/4 ounce and 5 other little 1 grammers in there to let them soak.

A couple days later I came back to get them and someone had stolen the nuggets. Well actually, I had just totally dissolved them in my homemade aqua regia. All that was left was remnants of the 1/2 ounce and the 1/4 ounce.

That was a hard lesson learned.

Doc
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#6 ARGONAUTE

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Posted 26 January 2011 - 01:14 PM

...snip... If one is using this acid care with skin, eye and vapour protection is required. It is best diluted 1 parts with 2 parts of clean water. .....snip...


Huego, aka Doc2... I might add this saftey tip for you...

never ever add water to acid!!!

soaking them DOC... ROFL!

#7 Huego

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Posted 26 January 2011 - 02:12 PM

Huego, aka Doc2... I might add this saftey tip for you...

never ever add water to acid!!!

soaking them DOC... ROFL!


True, that IS good general advice to those unfamilar with using acids.

BUT in fact you can get away with it either with all common acids except sulphuric acid! Because this is such a common acid its better to make this a blanket rule ........ add acid to water with gentle stirring. Without stirring (ie with a very dense acid like sulphuric) it will go straight to the bottom and then when stirred you could be in for a shock.

Huego
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#8 1dredger

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Posted 26 January 2011 - 08:53 PM

What is the best method for remove the dull glaze that is on gold after it has Mercury removed?
Swingin the 4000




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