Background: This research studied the feasibility of a simple method for extracting gold from central
processing units (CPUs) of computer circuit boards without solvent.
Methods: Ceramic and composite CPUs of computer circuit boards were used. Gold was extracted using a
hydrometallurgical method in six stages: grinding of CPUs, leaching in nitric acid, leaching in aqua regia,
removing the excess nitric acid, extracting the gold, washing and purifying the gold deposits. Measurements
of extracted precious metals were carried out by inductively coupled plasma (ICP).
Results: The results indicated that mean concentrations of gold in the first and second stages of leaching
were 0.138 and 31.16 mg/L, respectively. Following the washing stage, the concentration of gold in the final
deposit was 25 mg/L. The purity rate of the final deposit was 83.9%, and the final gold recovery yielded
82.3%.
Conclusion: The results of this study indicated there is a potential for extracting a high percentage of
precious metals from e-wastes without solvent.
Keywords: E-waste, Gold extraction, Hydrometallurgical metho
