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

Abstract:

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 (Fe_0.4Cu_0.6)_100-xPb_x 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.

• Periodical: Materials Science Forum (Volume 944)
• Pages: 1265-1270
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.944.1265
• Online since: January 2019
• Authors: Bin Chen, Jie He*, Jiu Zhou Zhao
• Keywords: Fe-Cu-Pb Alloy, Liquid-Liquid Phase Separation, Metal Recycling, Super Gravity, Waste Printed Circuit Boards

References

[1] J. Jia, J.Z. Zhao, J.J. Guo, Y. Liu, Immiscible Alloys and Their Manufacturing Technique, first ed., Harbin Institure of Technology Press, Harbin, (2002).

[2] B. Ghosh, M.K. Ghosh, P. Parhi, P.S. Mukherjee, B.K. Mishra, Waste Printed Circuit Boards recycling: an extensive assessment of current status, J. Clean. Prod. 94 (2015) 5-19.

DOI: 10.1016/j.jclepro.2015.02.024

[3] P. Hadi, M. Xu, C.S.K. Lin, C.W. Hui, G. Mckay, Waste printed circuit board recycling techniques and product utilization, J. Hazard. Mater. 283 (2015) 234-243.

DOI: 10.1016/j.jhazmat.2014.09.032

[4] A. Takeuchi, A. Inoue, Classification of Bulk Metallic Glasses by Atomic Size Difference, Heat of Mixing and Period of Constituent Elements and Its Application to Characterization of the Main Alloying Element, Mater. Trans. 46 (2005) 2817-2829.

DOI: 10.2320/matertrans.46.2817

[5] K. Shubhank, Y.B. Kang. Critical evaluation and thermodynamic optimization of Fe-Cu, Cu-C, Fe-C binary systems and Fe–Cu–C ternary system, CALPHAD, 45 (2014) 127-137.

DOI: 10.1016/j.calphad.2013.12.002

[6] B. Burton P, U.R. Kattner, The Al-Cu-Pb system (aluminum-copper-lead), J. Phase Equilib. 13 (1992) 309-317.

DOI: 10.1007/bf02667561

[7] L. Ratke, P.W. Voorhees, Growth and Coarsening: Ostwald Ripening in Materials Processing, first ed., Springer-Verlag, New York, (2002).