The purification of gold (removing contaminants) involves a technical and complicated process of heating the metal and treating it with chemicals. Purification is not obtainable by simply melting gold; it will just solidify again with the contaminants intact. Introducing chemicals to the gold when it is liquid will draw the contaminants out. The process involves toxic and dangerous risks. You should not attempt a home smelting process without proper understanding of such dangers and the chemicals involved.
Position a durable, burn-proof plate on a worktable with sufficient space. Put on your safety goggles, a workshop apron and burn-proof gloves for safety. Place the gold to be smelted in the center of the plate.
Fill a container with 30ml of nitric acid for every ounce of gold you're working on. Activate the solder tool and place it on the gold. Raise the solder temperature on the gold up to 710 degrees but less than 780 degrees to effect melting. Pour the melted gold into the container with the nitric acid. Wait for 30 minutes for the mixture to interact.
Pour hydrochloric acid, 120ml for every ounce of gold, into the container with the gold and nitric acid. Wait for 60 minutes for the mixture to interact. Look for the mixture to turn brown. Pour the contents of the container through a filter to catch the gold from the mixture. Look for the gold captured to be a clear, green color.
Pour water into another pot and raise the temperature with an oven until the water is boiling. Pour 1 lb. of urea into the boiling water. Stir the mixture and then pour it into the container with the treated gold. Pour slowly to allow the foaming action to dissipate. Pour in 1 oz. of storm precipitant into the mix per every ounce of gold. Allow the mixture to sit for 30 minutes.
Fill up a second pot with water and raise the temperature to boiling. Add the hot water to the mixture with the gold. Stir the mixture with the stir stick. Pull the gold out of the mix and place it back on a grill or platter where you can wash it. Rinse the gold with aqua ammonia repeatedly. Repeat the rinsing until you get no more white vapors. Let the gold dry.
Always wear protective safety gear such as goggles, apron, and gloves when handling chemicals and melting gold. Failure to do so can result in serious burns and injuries. Keep in mind many of these chemicals smell badly when reacting and this may cause neighbors to react or call the police or fire department not knowing what you are doing but sensing the smell. Avoid smoking or eating when performing a smelting process. Make sure the room has plenty of air flow and keep a first-aid kit handy in case of accident. Make sure the kit includes materials to treat chemical burns. Always work with an experienced smelter the first time you try this process.
Things You'll Need
Two large containers
Kiln or oven (optional)