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Electrolytic Recovery of Tin from Printed Circuit Boards (PCBs) Disassembled from Waste Liquid Crystal Displays (LCDs): Selection of H2SiF6 + H2SO4 + H2O2 Leaching Solution over Two-stage Leaching in HNO3 and HCl

Author(s): Sungkyu Lee, Kyoung-Hoon Kang, Jae Layng Park, Myung-hwan Hong, Soo-Young Lee, Sung-Su Cho, Hyun Seon Hong.

Abstract:

Waste PCBs (Printed Circuit Boards) from LCDs (Liquid Crystal Displays) contain valuable raw materials, Sn, Cu, and other noble metals. Among these, high purity tin was obtained by electro-winning after appropriate acid leaching of tin. For this, leaching and electro-winning process parameters were optimized for solution stability, dissolution and electrolytic efficiency. Two aqueous procedures were developed and tested for electro-winning at mass-production capable basis: (1) HCl leaching after preliminary HNO3 dissolution was quite effective in leaching high proportion of Sn as analyzed by ICP (Inductively Coupled Plasma) method. (2) Direct one-step leaching in H2SiF6 + H2SO4 + H2O2 was also tested and the solution was finally selected as electrolytes in electro-winning due to massproduction capability. The most efficient recovery of tin was observed after 7h electro-winning in aqueous H2SiF5 + H2SO4 + H2O2 maintained at 40oC: 96%-pure tin was obtained with 93.2% recovery rate.

Keywords: Electronic waste, LCD, leaching solution, PCB, recovery, Tin.

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Article Details

VOLUME: 10
ISSUE: 1
Year: 2014
Page: [104 - 107]
Pages: 4
DOI: 10.2174/1573413709666131108233753