GOLD RECOVERY FROM DIFFERENT PARTS OF PC E-WASTE.

Annually about 300 metric tonnes of gold are used in electronic devices in the world. After the end of use, they become e-waste and are recycled or put on the landfills. Recycling rate of e-waste in Slovakia was in 2017 according to Eurostat only 36.7 %. Recent studies show that yields from e-waste (mainly computers, mobile phones) are much higher than in metal ores and thus can be considered as valuable secondary sources of precious and base metals. In presented paper five different parts of computer e-waste were investigated for possible gold recovery, namely CPUs, CPU sockets, BGA chips, pins from motherboards and flexible wires from monitors. All parts were mechanically pre-treated with suitable techniques to maximize gold concentration in samples. For gold recovery two-step hydrometallurgy leaching process was applied. In first step base metals were dissolved (Cu, Ni, Zn, Sn and Pb) using either HCl + H₂O₂ mixture or HNO₃. Second step consisted in applying Aqua Regia to dissolve gold. For precipitation of dissolved gold sodium metabisulfite was used. All gold obtained was weighted in dust form. Relative yields from all parts are as follow: flexible wires – 3.27 %, BGA chips – 0.93 %, CPUs – 0.20 %, MB pins – 0.06 %, CPU sockets 0.01 %. [ABSTRACT FROM AUTHOR]