Recovery Of Gold From Electronic Waste Through Non-Cyanide Based Electrodeposition Technique

• Main Author: Nazri, Amirul Islah
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: T Technology; TP155-156 Chemical engineering
• Online Access: http://eprints.usm.my/45784/1/Recovery%20Of%20Gold%20From%20Electronic%20Waste%20Through%20Non-Cyanide%20Based%20Electrodeposition%20Technique.pdf; http://eprints.usm.my/45784/

The continuous production of electronic equipments due to technological advancement has lead to continuous increase in electronic waste (E-waste) production. Typical E-waste contains precious metals, with the most valuable one is gold. In the coming years, with the increasing amount of E-waste produced that posed as environmental pollution, the amount of gold that will be going to be wasted in the dump site will be also keep increasing, if no proper recovery process takes place. Conventional methods for gold mining are currently being applied to recover gold from E-waste, through cyanide based routes. However, there are high risks in using this method as the wastewaster from the cyanide leaching is harmful to both human and environment. Hence, in this project, a non-cyanide based reagent namely thiourea (TU), has been chosen and used in the gold recovery process by means of electrodeposition technique. In addition to this, an in-situ gold leaching with the acidic TU solution used for the gold recovery process tends to occur in parallel with the gold electrodeposition process. Thus, more studies has to be made to optimize both acidic TU leaching of gold, and gold electrodeposition processes in order to recover as much gold as possible from the computer RAMs sample. The E-waste sample in this research were provided by industrial research partner, the Scrap Computer Trading (SCT) Sdn. Bhd. Without undergoes any optimization process and copper removal pre-treatment process, about 5 to 7 wt. % of gold tends to leach from the crushed RAMs sample via acidic TU leaching. After removing copper, the amount of gold leached increase to about 40 wt. % in the absence of oxidant. By using the optimized parameters, with the presence of hydrogen peroxide (H2O2) as oxidant, about 72 wt. % of gold were able to be succesfully leached out from the pre-treated RAMs samples via the leaching process. Finally, about 5 wt. % of gold from the leached solution were able to be deposited on the stainless steel cathode through electrodeposition process. At this stage, although the amount of gold deposited is still quite small, the recovery through gold leaching process has been significantly improved based on the optimization carried out. Further research to widen the scope of optimization into the deposition process is required to achieve better results on the gold deposition process.