Recovery Gold from Waste Printed Circuit Board of Computer

The parts without gold and copper were torn down from the waste printed circuit board (PCB) of computer by simple handwork, and the remaining parts of waste were burned at 700 degrees C to remove the most organics. 30% sulfuric acid was used to leach copper from the burned waste (ash) with a solid to liquid ratio of 1:3 (W/V) at 100 degrees C. Ferrous powder was applied to reduce the Cu2+ from the leaching solution. The leaching efficiency and total recovery of copper were 98.75 and 92.0% respectively. After copper recovery, the remaining ash was mixed a 30% of the mixed acid (HNO3:HCl=1:8) to leach gold with a solid to liquid ratio of 1:3 (W/V) at 100 degrees C. The leaching effeciency of gold was over 99%. Activated carbon was applied to adsorb gold from the leaching solution, and then was burned at 650 degrees C for 1.5 h to form gold-contained ash. An aqua regia was applied to dissolve the gold from the ash. Gold was reduced from the solution by zinc powder. Its total recovery of gold is 98.3%.