Investigation and recovery of copper from waste silicon solar module

Abstract

Photovoltaic (PV) technology has seen exponential growth in the last few decades with the total global installation reaching 849 GW by year 2021. With the estimated solar waste of nearly 78 million tonnes by year 2050, its high time to emphasise on the development of the recycling processes for valuable materials contained in end-of-life (EoL) solar panels. Crystalline silicon (c-Si) technology, owing to the largest market share, is forecasted to generate the majority of solar waste flux. A c-Si panel contains metals like Ag, Cu, Al, Pb and Sn. Most of the metallic fraction (Cu, Pb and Sn) by weight is contained in the connecting wires of the panel. In the present study, a process is developed for recovery of metallic Cu along with Pb and Sn without their exposure to the environment. Initially, connecting wires were separate out from panel using toluene solution. These wires were then thermally treated at 800 °C for 7 h in a sealed quartz tube to get impure Cu strips and Pb-Sn powder. A set of chemical reactions was carried out next to first recover CuO powder followed by subsequent treatment with H2SO4 and Zn dust to recover 97.27% pure reddish brown Cu powder. As high purity copper powder with a good recovery rate of around 90% is obtained as the end product, the present study demonstrates a very simple process to recycle connecting wires in an ecological way with trapping toxic Pb and Sn.