How to Separate Precious Metal

Large gold nugget
  • 2 hours
  • Advanced
  • 2000-5000
What You'll Need
Tilting furnace
Gold-plated circuit
Sodium borate

A wide variety of different types of electronics and other household objects contain at least one type of precious metal. In many cases, the trace amounts of these metals are fused together inside of the object. In order to recover those metals once the object has worn out or broken, you'll need to properly know how to separate the metal. Adsorption, a process of separating out metal solids from liquid solutions, is common, as is smelting, a process that removes different types of metals from one another. Read on for a brief guide on separating out the most common type of precious metal at home.

Step 1 - Heat Up the Circuit

Ensure that you know exactly how to safely operate your tilting furnace. Be sure to also wear any protective equipment that is necessary prior to using the furnace. When you're ready, insert the circuit into the furnace and begin to heat the furnace. Monitor the temperature inside the furnace closely, and allow it to continue to heat up until the temperature inside of the furnace is approximately 1200 degrees C (or about 2192 degrees F).

Step 2 - Create the Slag

The "slag" is the liquid metal mixture that will be the result of the temperature being raised to the high level that it is. To create the slag, you'll need to mix in the silica and the sodium borate chemicals into the furnace and on top of the gold-plated circuit. Do this according to the usage instructions of your particular furnace and ensure that you remain safe at all times. The silica and sodium borate are collectively known as "fluxes" in this procedure.

Step 3 - Allow Time for the Metals to Dissolve

The slag will not develop instantly. Rather, it will take about an hour and a half for the metals to dissolve. If the metals have not dissolved completely during this time, raise the temperature of the furnace to about 1400 degrees C (or about 2552 degrees F).

Step 4 - Observe the Gold Separating

Continue to heat the slag until you can observe the molten gold begin to dissolve away from the rest of the slag. This occurs because of the melting point and the density of the gold as compared with the different melting points and densities of the other metal components of the slag. The gold should slip down into the smelting vessel.

After this occurs, you can cool and remove the gold from the smelting vessel and also remove the slag as well. It's common at this point to refine the gold through a separate refinement process to ensure a high level of purity. For more information on refinement procedures of this type, consult with a blacksmith or an experienced smelter in your area.