According to the U.S. Geological Survey, obsolete computers contain considerable amounts of recoverable materials, including gold from their printed circuit boards. In fact, one ton of computer scrap contains more gold than 17 tons of gold ore.
Manual Recovery
A simple, but labor-intensive, method of recovering gold from circuit boards is to manually scrape it from the edges of connectors and other parts of the board. This method requires time and patience, but can recover a high percentage of gold.
CBX
The method of gold recovery known as CBX involves dissolving the non-gold material of a circuit board with a strong acid, such as hydrochloric acid (HCl). It is only suitable for recovering gold from the edges of connectors, or "fingers," of the board and much of the gold is lost during recovery.
Aqua Regia
Aqua Regia is mixture of concentrated hydrochloric acid and concentrated nitric acid (HNO3) in a ration of approximately 3:1. It may be used to dissolve gold from circuit boards into solution, and the gold can be recovered by evaporating the solution with heat.
