Re: Gold refining in a nutshell.

Why the copper? No mention of any flux to keep that copper from oxidizing
in the melt. Why no mention of the proper strength of Nitric acid? Too
strong acid causes your Gold to break apart into a powder that is extremely
difficult to remove from the solution. Use Pyrex --- not stainless steel.

In fact there are so many things wrong with this procedure that perhaps the
proper subject line should have been "Gold refining from the nuthouse."

In point of fact any alloy less than 990 fine in combined Gold and Silver
can not be parted without the gold disintegrating with some of the Gold
particles so fine that they cannot be removed from suspension. "Quartering"
is better known to the refining trade as "Inquarts" and the metal used is
Silver. If there is 2 1/2 - 3 times more Silver than Gold in the resulting
"shot", and if the "shot" is rolled to .010 inch thickness, and if 1.06 s.g.
Nitric Acid is used (first heat the acid until vapor can be seen rising from
it, then add the rolled alloy. If it does not immediately begin to dissolve
then add 1.26 s.g. Nitric Acid a droop at a time until it does.) the base
metals and Silver will quietly dissolve into the acid and the rolled alloy
can be seen to shrink without breaking apart. When the action of the acid
ceases, carefully pour off the solution into another beaker and add enough
1.26 s.g. Nitric acid to cover the remaining metal and heat to just below a
boil and hold there for 10 - 30 minutes. Then pour the acid into the beaker
with the previous solution. Cover the remaining metal with distilled water
and bring to a boil. This will remove most of the Silver Nitrate remaining
in the Gold. Repeat the distilled water wash twice more. You can now
"anneal" the remaining Gold which will change it from a brownish-black,
amorphous mass to the familiar yellow of Gold. An experienced eye can tell
the relative purity of the Gold by its color.

After annealing the additional Aqua regia step can be done to recover Fine
Gold of .999 or better fineness.

As Peter so nicely puts it, anyone wanting to try their hand at refining
Gold will be well ahead of the game by doing a lot more reading than a post
to a newsgroup.

--

Don Thompson

Remmy sez,
Count de Monet.
Unless, of course, you are Baroque.


"bigmoe" <halliburgers@xxxxxxx> wrote in message
news:vqiik1hef4sjbj117vcbb53qtvhm17q93q@xxxxxxxxxx
This process involves a two-step acid dissolution using nitric acid and
aqua regia followed by reconstitution of gold.

1. Get all your gold together and figure out how much pure gold you
have by weight. This may require melting a bar and having it assayed,
but if you are pretty good at testing gold you can figure it out
arithmetically.

2. Melt your gold in a crucible kiln and add 4 parts of copper to
every part of pure gold. This is called "quartering." Once your
copper/gold mixture is thoroughly melted and orange hot, empty your
crucible using tongs and heat resistant gloves over a large barrel full
of water to make copper/gold shot. Be careful not to drop the hot
crucible in the water this can result in an explosion and injury. Use
appropriate safety equipment including heavy aprons and welder type
masks.

3. Empty the barrel and recover your shot. Place your copper/ gold
shot in an industrial size stainless steel pot over a hot plate set at
medium heat, if you have small quantity of shot you may use a large
glass beaker instead. Add enough nitric acid to thoroughly cover the
metal, approximately twice the height of the metal itself. This will
cause immediate bubbling and dissolution of copper, silver and other
metals resulting in a thick blue liquid. Copious fumes are being
released so be sure you do this under a hood with excellent extraction
or out in an open area where it is permitted. Use proper gas masks.
Once the acid stops dissolving metal it needs to be replaced with fresh
acid. Empty the old acid into a holding tank taking care not to empty
out the gold material and replace it with new acid. Several "attacks"
maybe needed until all that remains is a brownish powder, this is
nearly pure gold, about .995 pure.

4. Following your last attack carefully rinse your gold powder until
the acid is removed then slowly dry the material over a hot plate at a
low temperature. Place the gold powder in a large beaker containing
Aqua Regia (3 parts nitric acid to one part hydrochoric acid) over low
heat, this is one of the only solvents strong enough to dissolve high
grade gold. Lower grade golds cannot be dissolved this way because
silver chlorides form and stop the process. That is why the two step
process is required.

5. Once your gold is completely dissolved the aqua regia will turn a
clear golden color. The aqua regia then needs to be neutralized by
slowly adding "urea," an alkaline material which is available at feed
stores. Do not add too much at once or a violent reaction will occur
causing the liquid to spill. Once the addition of urea no longer cause
the liquid to react, the acid has been neutralized.

6. To this golden liquid is added sodium bisulfite or ferrous
sulphate which causes the gold to reconstitute from the liquid and
precipitate to the bottom of the vessel. Remove the acid taking care
not to spill any gold and rinse thoroughly until all acid is removed.
It is wise to use a Buchner funnel with paper filter since small
amounts of gold may be spilled.

7. Dry the gold and melt once again. You now have gold that is .999
pure or better. Dont throw out your leftover liquids, there is silver
in that solution which may be recovered through processes beyond the
scope of this note.

Big Moe in Miami



.

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