Author(s): Oh CJ, Lee SO, Yang HS, Ha TJ, Kim MJ
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Abstract This study was carried out to recover valuable metals from the printed circuit boards (PCBs) of waste computers. PCB samples were crushed to smaller than 1 mm by a shredder and initially separated into 30\% conducting and 70\% nonconducting materials by an electrostatic separator. The conducting materials, which contained the valuable metals, were then used as the feed material for magnetic separation, where it was found that 42\% of the conducting materials were magnetic and 58\% were nonmagnetic. Leaching of the nonmagnetic component using 2 M H2SO4 and 0.2 M H2O2 at 85 degrees C for 12 hr resulted in greater than 95\% extraction of Cu, Fe, Zn, Ni, and Al. Au and Ag were extracted at 40 degrees C with a leaching solution of 0.2 M (NH4)2S2O3, 0.02 M CuSO4, and 0.4 M NH4OH, which resulted in recovery of more than 95\% of the Au within 48 hr and 100\% of the Ag within 24 hr. The residues were next reacted with a 2 M NaCl solution to leach out Pb, which took place within 2 hr at room temperature.
This article was published in J Air Waste Manag Assoc
and referenced in Journal of Advanced Chemical Engineering