Things You'll Need
Protective eyeglasses or goggles
Respirator face mask
Scrap gold (jewelry or fine gold)
Graphite carbon crucible
Blow torch (oxy-acetylene)
You can melt scrap gold at home to purify it using a few specialized tools and some common materials you can purchase at your local hardware store. Pure gold is 24 karats and has a melting point of 1,940 degrees Fahrenheit. If a piece of gold jewelry is labeled as having less than 24 karats (e.g., 14 karats), it means the jewelry piece is an alloy containing other metals in addition to gold to make it stronger. Gold dust and flakes obtained from prospecting is known as "fine" gold and it usually contains some impurities that need to be flushed out with a flux mixture. The flux also keeps the fine gold from blowing away when a blow torch is turned on it.
Protect yourself before you begin by donning heat-resistant gloves, glasses or goggles, and a respirator face mask.
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Put your scrap gold in the crucible until it is completely full. A crucible used for melting gold looks similar to a bowl with no lid or top on it. Add a few pinches of sodium carbonate and a few pinches of Borax for your flux.
Turn on the torch and very slowly touch it to the gold itself in the crucible. Keep torching until all gold melts down to molten form. Use the crucible tongs, if necessary, to break up any pieces that won't dissolve.
Pour the liquid gold very slowly and carefully with the tongs into a bar-type mold.
Allow to completely cool and harden. Unscrew the two-part mold before removing the solid gold.
Don’t use a ceramic crucible in this case because it could spring a leak and spew molten gold onto you.