Preliminary Study of Hydrometallurgical Extraction of Silver from Selected E-Waste

part of electronic devices used to open or close circuits by using
electronic components without any mechanical operation. After
decommissioning, it can be considered as an important source of
base and precious metals with high economic value. The annual
growth rate of about 4-5 % in 2016 is one of the fastest growing
waste stream, and only about 20 % of e-waste is recycled. After the
use-phase, electronic devices become electronic waste (e-waste);
consequently, it is important to consider e-waste as a secondary
supply for the recovery of precious metals. In this study, a simple
hydrometallurgical recovery method for silver (Ag) extracting from
used electronic relays was performed. The silver extractions
consisted of six stages: disassembling of relays, removal of base
metals, leaching in nitric acid, precipitation, conversion silver oxide
and melting. Measurements of extracted precious metals were
carried out by scanning electron microscope (SEM) and EDS
(Energy Dispersive Spectrum) analysis. The purity rate of the final
deposit was 94.9 % on the surface of the sample, and the final silver
recovery yielded 0.44 % of the raw material. During the second
stage of the experiment, mixed types of electronic relays were used
to compare the yields. Electronic relays can be considered as an
important source of base and precious metals with high economic
value. The final yield of the mixed electronic relays reached up to
0.54 % of Ag with the purity of over 95 %.