Flexi Says: The old computers contain silver and gold. The circuit board contains silver, copper, gold and the microprocessor contains only gold. The old computers are sent to a plant that extracts these precious metals. Firstly, the outer body, cables of the computer are removed and you left with the chips and processor. A mixture of HCl and HNO3 is used to separate gold from ceramics by placing a microprocessor in the solution. The gold dust so obtained from this process is melted and cooled to make gold bullion. While the other parts contained a mix of these precious metals so they are melted and then cooled to form a plate that consists of gold, silver, and copper. After this through the process of electrolysis, the copper and silver are separated and the gold so left behind is again melted and cooled to gold bars.