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How to Refine a Gold Smelt
By Lisa
Parris
In nature, gold nuggets are not pure gold. They
are a combination of minerals, known as ore.
The metal can be removed from the ore in a
process known as smelting, in which the minerals are separated by melting
point.
Smelt gold is more pure than the original ore
product, but can still contain impurities such as silver, copper and platinum.
A second refinement can be done by dissolving
the smelt gold in a combination of acids; a method known as aqua regia
refinement. The result is gold that is 99.95 percent pure.
Weigh your gold smelt. For every ounce of gold,
you will need a container with a 300-milliliter capacity.
So, if you're refining 5 ounces of gold, you
will need a 1500 milliliter container, or about 1 ½ quarts.
Add 30 milliliters of nitric acid for every
ounce of gold. So, if you're refining 5 ounces of gold, you would need to add
150 milliliters to the container.
Allow the gold to sit in the nitric acid for 30
to 45 minutes.
Add 120 milliliters of hydrochloric acid for
every ounce of gold in the container. For 5 ounces of gold that would be 600
milliliters of HCL.
The addition of hydrochloric acid turns the
mixture brown and can result in fumes.
As the chemicals react and heat up, the gold
will dissolve. Let the mixture sit for 1 to 8 hours to cool off.
Line the funnel with filter paper and pour the
acid through the filter and into another, larger container, stopping before any
particles are poured off.
The filtered acid should be green and clear. If
the acid is cloudy, filter it again.
Boil 1 quart of water. Remove from heat and add
1 pound of urea.
Slowly add the urea mixture to the acid. This
will cause an acid/base reaction, much like the old school volcano using baking
soda and vinegar.
The acid will foam up, so don't pour too quickly
or you'll have a huge mess on your hands.
When the mixture stops foaming, stop pouring
urea in. All the nitric acid has been neutralized.
Boil a second quart of water. Remove it from the
heat and stir in Storm. For every ounce of gold, add 1 ounce of Storm
precipitant.
So, for 5 ounces of gold, add 5 ounces of Storm.
(If using a different gold precipitant, follow the package directions).
Slowly stir this solution into the acid. The
solution will turn a muddy brown color and emit a strong odor.
Wait 30 to 45 minutes. Check the acid for
dissolved gold. To do this, take the end of the stirring rod and insert it into
the acid.
Remove the rod and touch it to a paper towel,
creating a wet spot.
Add one drop of gold detection liquid to the
spot on the paper towel. If the spot turns dark, there is still gold in the
acid. If you see this, give the Storm more time to work or add more precipitant
to the acid.
When the acid has separated into layers, with a
clear amber top and a muddy brown bottom, pour off the top layer into another
container.
Be careful not to pour off any of the mud at the
bottom as the mud is your gold.
Add water to the mud when the acid has been
poured off. Stir vigorously and allow the mud to settle. Repeat, rinsing the
mud with water 4 times.
Rinse the mud with aqua ammonia. When the aqua
ammonia is added, white vapors will form as the remaining acids are
neutralized.
Rinse the gold mud a final time using distilled
water. When it settles, pour off the water and scrape the mud into a heat proof
bowl.
Place the bowl on a hot plate and allow it to
dry.
When the dry mud is melted and allowed to reform
it will take on the appearance of metal and will be 99.95 percent pure.
Things You'll Need
Scale
Heavy duty plastic buckets
Wooden rod to stir with
Safety goggles
Rubber gloves
Rubber apron
Nitric acid
Hydrochloric Acid
Filter paper
Funnel
Water
Urea
Gold selective precipitant, such as Storm
Paper towels
Precious Metal Detection Liquid
Aqua ammonia
Distilled water
Heat proof bowl
Hot plate
Tips
If there was platinum in your gold, it will not
be dissolved by the acids and will be left behind in step 4. Always save your
precipitants- you never know what you may get.
Warnings
This method uses strong acids which can be
harmful if spilled on the skin or if ingested. They also generate fumes which
can irritate the respiratory system.
Work in a well-ventilated area and use
protective clothing. Neutralize any acid spills with a liberal application of
baking soda.
Lisa
Parris is a writer and former features
editor of "The Caldwell County News." Her work has also appeared in
the "Journal of Comparative Parasitology," "The Monterey County
Herald" and "The Richmond Daily News." In 2012, Parris was
honored with awards from the Missouri Press Association for best feature story,
best feature series and best humor series.
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