Leaching of lead from solder material of waste printed circuit boards (PCBs)

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• 作者：Manis Kumar Jha^a ; ^{mkjha@nmlindia.org} ; Archana Kumari^a ; Pankaj Kumar Choubey^a ; Jae-chun Lee^b ; ^{jclee@kigam.re.kr} ; Vinay Kumar^a ; Jinki Jeong^b
• 关键词：Recycling ; Printed circuit boards (PCBs) ; Solder ; Lead ; Leaching
• 刊名：Hydrometallurgy
• 出版年：2012
• 期刊代码：38_0304386x
• 类别：ce
• 出版时间：June, 2012
• 卷：121-124
• 期：Complete
• 页码：28-34
• 文件大小：1385 K

摘要

Present work is focused on the selective leaching of lead from the soldering material present on the outer layer i.e. epoxy resin of waste PCBs, liberated through a novel pre-treatment technique of organic swelling using n-methyl-2-pyrrolidone. Nitric acid was found as a suitable leachant to dissolve lead. Initially, the effect of temperature, S:L ratio, leaching time and acid concentration on leaching of lead was investigated using fresh solder material containing 47.36%lead and remaining tin. With 0.2 M HNO₃ at S:L ratio 1:100 (g/mL) and temperature 90 掳C, 99.99%lead was leached in 120 min. Leaching kinetics followed 1 鈭?#xA0;(1 鈭?#xA0;X)^1/3 = K_ct i.e. chemically controlled reaction model with activation energy 26.94 kJ/mol. Validation of lead leaching from solder of liberated epoxy resin of swelled PCBs indicates that 99.99%of lead could be leached out at 90 掳C with 0.2 M HNO₃ in 45 min. Tin left in the residue of the liberated resin was further leached with 3.5 M HCl at 90 掳C for 120 min at S:L ratio 1:20 (g/mL), which dissolve almost 98.74%tin. Then, metal free epoxy resin was washed with water to utilize it or dispose-of safely without affecting the environment.