Leaching studies for the recovery of tin from the solder of waste printed circuit boards

Choubey, Pankaj K and Jha, Manis K and Kumar, Vinay and Jeong, Jinki and Lee, Jae-chun (2010) Leaching studies for the recovery of tin from the solder of waste printed circuit boards. In: Proceedings of the XI International Seminar on Mineral Processing Technology (MPT-2010), Dec 2010, NML Jamshedpur, India.

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Printed Circuit Boards (PCBs) are one of the important components of electrical and electronic equipments, which contain valuable, precious and hazardous metals besides the other materials such as plastic, glass etc. Large quantities of waste PCBs from different equipments are generated due to the replacement of old one with the launching of new and efficient models with advance features. The recycling of such waste materials is necessary to conserve the limited resources and also to protect the environment. Present paper is focused on the recovery of tin from solder material used in PCBs for fixing the various electronic components such as capacitor, resistor, connectors etc. Metals layers of PCBs are separated by swelling of the resin using organic solvent as an alternative traditional mechanical pre-treatment process. The main focus of the paper is the leaching of lead and tin from epoxy resin obtained after the liberation of thin metal sheet from organic swelled PCBs. Therefore, the leaching studies were carried out with pure tin metal and solder materials (52.6 % Sn and balance Pb) under varying hydrochloric acid concentration, temperature at fixed pulp density 10 g/L. The experimental data indicated that the 88.1% pure tin was dissolved with 9M HCl at 90°C within leaching time 1hr 15 min, however percentage dissolution was found to increase up to 98% with increase in leaching time to 2 hrs 45 min. The dissolution of tin from the solder was found to be 99.99% with 5M HCl at 90°C in 1hr 15 min. The kinetics of leaching of tin from solder was studied in hydrochloric acid. Leaching reaction followed “film diffusion control dense shrinking sphere model” with rate equation 1–(1–X)2/3 = Kct. The optimized condition obtained from these studies will be useful for the removal of tin from solder material of waste PCBs and lead metal remained in the residue could be leached out by nitric acid for safe disposal or utilization of resin residue to the environment.

Item Type:Conference or Workshop Item (Paper)
Official URL/DOI:http://www.nmlindia.org
Uncontrolled Keywords:Leaching, Tin, Waste printed circuit boards.
Divisions:Metal Extraction and Forming
ID Code:2590
Deposited On:16 Mar 2011 17:49
Last Modified:15 Nov 2011 14:42
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