Separation of Sn, Bi, Cu from Pb-free solder paste by ammonia leaching followed by hydrochloric acid leaching

A recycling process consisting of swelling, ammonia leaching and hydrochloric acid leaching was developed to recover Sn, Bi, Cu, and resin from Pb-free Sn-Bi-Cu solder paste. The resin was separated from metal powder by swelling the solder paste in methyl ethyl ketone at 30°C, 200rpm and 5% pulp den...

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Bibliographic Details
Published inHydrometallurgy Vol. 169; pp. 26 - 30
Main Authors Jeon, Sang-Hee, Yoo, Kyoungkeun, Alorro, Richard Diaz
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.05.2017
Subjects
Ammonia leaching
Hydrochloric acid leaching
Lead-free solder
Recycling
Lead-free solder
Ammonia leaching
Recycling
Hydrochloric acid leaching
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Summary:A recycling process consisting of swelling, ammonia leaching and hydrochloric acid leaching was developed to recover Sn, Bi, Cu, and resin from Pb-free Sn-Bi-Cu solder paste. The resin was separated from metal powder by swelling the solder paste in methyl ethyl ketone at 30°C, 200rpm and 5% pulp density. The addition of distilled water precipitated the resin from methyl ethyl ketone. The recovered resin was confirmed to be epoxy resin by FT-IR analysis. Ammonia leaching followed by hydrochloric acid leaching was performed to separate Cu, Sn, Bi sequentially from metal powder. Copper was solubilized easily with leaching efficiency reaching 100% within 15min under the following conditions: 5M NH3 solution, 1M (NH4)2CO3, 0.1M CuCO3, 50°C, and 1% pulp density. Tin and bismuth were recovered as leach residue in the ammonia leaching. Tin was selectively leached in 0.5M HCl solution with 10,000mg/L Sn4+ and 1% pulp density at 50°C and 400rpm, while Bi was not detected in the leach solution. The recycling process has successfully separated Sn, Cu, Bi and resin. •A solder-paste recycling process was proposed to separate resin, Sn, Bi & Cu, respectively, by swelling & leaching processes•Epoxy resin could be recovered by swelling with methyl ethyl ketone followed by distilled water addition•Cu can be dissolved by ammonia leaching leaving Sn & Bi as leach residue from metal powder obtained from the swelling process•Sn could be selectively leached from Sn and Bi powder using HCl solution with SnCl4.
ISSN:0304-386X
1879-1158
DOI:10.1016/j.hydromet.2016.12.004