Environmentally friendly recycling process for crystalline silicon photovoltaic modules: Airflow separation and AlCl3·6H2O + H2O2 etching system

Abstract

The disposal of crystalline silicon photovoltaic modules (c-Si PV modules) at the end of their service life (EoL) is a pressing issue that requires attention. In this study, an environmentally friendly and efficient recycling method was proposed, involving pyrolysis, airflow separation, and AlCl3·6H2O + H2O2 etching. After removing the backsheet, EoL c-Si PV modules were pyrolyzed to eliminate ethylene vinyl acetate (EVA) as an encapsulant. A gas/solid fluidized bed was employed to separate solar cells and glass particles mixed together after pyrolysis. The findings of the study indicate that, under specific parameters including a bed height of 6 cm, an airflow velocity of 58.82 m3/(L·h), and a separation time of 5 min, the separation process achieved remarkable efficiencies. Notably, the recovery efficiency and product purity for samples with particle sizes of d > 4 mm and 2 < d ≤ 4 mm were recorded at 100 % / 99.37 % and 100 % / 95.50 %, respectively. The experimental results demonstrated that, under the conditions of 0.6 mol/L AlCl3·6H2O, 2 % H2O2, and a temperature of 80℃ for 30 min, a significant removal of 95.32 % for Ag and 99.77 % for Al was achieved. This finding illustrates the effectiveness of the selected reagents in the etching process. The insights gained from this paper contribute valuable knowledge to the optimization and understanding of the separation and etching processes employed in solar cell separation.