Phase Separation of Fe-Cu-Pb Alloy and Recycling of Mixed Metals in Waste Printed Circuit Boards

The pyrolysis experiment was carried out on the waste printed circuit boards (WPCBs) of mobile phones to obtain the mixed metals which contains more than ten valuable metals. The main components in the mixed metals are elements Fe, Cu, Pb, Sn. The liquid-liquid phase separation behavior of (Fe0.4Cu0.6)100-xPbx ternary alloy has been studied. The introduction of Pb into the metastable immiscible Fe-Cu alloy can result in a stable liquid-liquid phase separation into L(Fe) and L(Cu,Pb) liquids. With the increasing of Pb content, the second phase separation in the residual L(Cu,Pb) liquid was detected, resulting in the formation of three-zone-separation structure. On this basis, a hierarchical separation system was designed to recycle mixed metals in super gravity field. The results show that the metals Cr, Co, Ni, Si are mainly enriched in the Fe-rich zone, the precious metals Au, Ag and a small amount of Zn are concentrated in the Cu-rich zone, while the low-melting-point metals Sn, Bi, Cd, and In are collected in the Pb-rich zone.