Experimental and numerical study of extracting silver from end-of-life c-Si photovoltaic solar cells in rotating systems

The end-of-life (EoL) c-Si photovoltaic (PV) solar cell contains valuable silver, and chemical leaching can extract silver from the cell. However, limited works have been reported on the leaching kinetics and hydrodynamic behaviour of silver leaching process. In this work, an integrated experiment and numerical study are conducted to understand and optimise the silver leaching process in rotating systems. First, the lab-scale physical experiments are conducted to obtain a reaction kinetics model of silver leaching from PV cells. Then, a CFD-DEM model is developed to describe the reacting flow details related to solar cell particles' leaching process including this kinetic model. The model is validated against the lab measurement in terms of flow pattern and leaching performance. Then the CFD-DEM model is applied to a larger rotating system and studies the effects of rotator speed, rotator length, and rotator shape on leaching efficiency. The simulation results indicate that the particles inside the reactor experience mixing, transition, and suspension states with increased rotator length and rotator speed. In the transition state, the particles accumulate near the wall and form a packed bed, leading to the lowest leaching efficiency. In the suspension state, the particles are well fluidized and form a loose, ring-like particle wall. The leaching efficiency has a positive relationship with the fluidization level of the solid phase. The results also show that the leaching efficiency drops when linearly scaling up the reactor size while fixing other operating conditions. This work lays a foundation for process scale-up and optimization of EoL PV panel recycling.