Leaching of Lead from Solder Material Used in Electrical and Electronic Equipment

Present work is a part of developing novel recycling technique for waste printed circuit boards (PCBs) i.e. the liberation of metals from PCBs by organic swelling followed by the treatment of resin to remove/ recover hazardous soldering materials. In order to recover the hazardous metallic constituent lead from the liberated resin, initially the leaching studies were made using fresh solder containing 63.9% Pb and remaining tin. Experimental results obtained in different conditions viz. time, temperature and acidity showed ~97.20% of lead dissolution with 6M HNO3 at solid to liquid (S:L) ratio 1:10 (g/mL) and temperature 90C in 75 minutes. The result of the studies validated with crushed PCBs shows that almost total lead and tin was leached out with 6M HNO3 and 6M HCl respectively at S:L ratio 1:10 (g/mL) and temperature 90C within 50 minutes. The results will be useful for the treatment and safe disposal of PCBs resin. Introduction Global economical growth and technological advancement resulted in the incredible increase in the volume of electrical and electronic equipments (EEE) being procured by the consumers with replacement of used EEE [1]. Therefore, huge amount of waste EEEs generation takes place globally, specially in industrialized countries such as India, China, Greece etc. India is one of the fastest growing economies countries of the world and the growth in PC ownership per capita during the period 1993 2000 increased to the extent of 604%, compared to a world’s average of 181% [2]. As India is the second most populous country with over 1 billion population, the quantity of e-waste generation is also high, respectively. These electronic products are made up of variety of components. Printed Circuit Boards (PCBs) are essential component in advanced EEE, and its recycling is one of the major challenges. The surface of the PCBs mainly contains the Cu metal circuits which is usually covered by a layer of epoxy resin and solder material, which is an alloy of lead and tin. Direct leaching of metallic fractions encapsulated with plastics, reinforced resins and ceramic rarely accomplishes effective extraction of metals from these waste PCBs [3]. Metal recovery using hydrometallurgical technique readily involves the leaching process in order to reduce the volume of the waste material and to recover selectively valuable as well as the perilous metals. In pyrometallurgical recycling processes, traditional methods such as incineration, melting etc are employed to recover precious and non ferrous metals from e-waste