Physical and chemical treatment of end of life Si-based and CdTe photovoltaic panels

Photovoltaic panels are the emerging technology converting solar radiation into electrical energy, which is expected to provide a fundamental contribution to the shift from traditional fossil fuels to renewable energy-based economies. European community has extended regulations for the treatment of end-life electrical and electronic wastes in order to include the disposal of photovoltaic panels. The legislation currently established collection rates for photovoltaic modules up to 85% and recycling rates up to 80%. In this work different kinds of panels (Si-based panels and CdTe panels) were treated by a process route made up of the following operations: mechanical pretreatment, sieving, and dedicated chemical treatment by solvent or acid of different fractions emerging from pretreatment. More specifically, after crushing, three fractions were obtained: a coarse fraction (>1 mm) requiring further chemical treatment by solvent in order to separate EVA-glued layers from glass fragments; an intermediate fraction (0.3-1 mm) of metal polluted glass requiring further treatment by acid leaching; a fine fraction (<0.3 mm) which could be further treated for precious metal recovery (mainly Ag and Cu). Coarse fractions (72% w/w) were treated by solvent giving recoverable glass fraction (56%w/w), plus metallic contacts, back sheets and EVA. All fractions below 1mm were sieved and chemically characterized for metal content. Intermediate fraction (0.3-1 mm), which are 13 %w/w, were fed to acid leaching in order to obtain another recoverable glass fraction eliminating metal impurities of Fe, Al and Zn. Fine fraction (< 0.3 mm) can be treated for extraction of precious metals (Cu and Ag). The process route allowed to treat by the same scheme of operation mixed feed of Si based panels and Cd-Te panels with an overall mass recovery yield of 85%w/w.