Recycling Si in waste crystalline silicon photovoltaic panels after mechanical crushing by electrostatic separation

The photovoltaic (PV) market started in 2000, and the first batch of crystalline silicon (c-Si) PV panels with a lifespan of 20–30 years are about to be retired. Recycling Si in waste c-Si PV panels is critical for resource reuse and environmental preservation. Electrostatic separation is a non-polluting and low-cost technology for recovering Si from mechanical crushing products of c-Si PV panels. In this study, the waste c-Si PV panels were pretreated by mechanical crushing and the products contained two parts: the blocks and the mixed powder. Through acid washing and X-ray fluorescence tests, a mass fraction of 82.8 wt% of Si in the crushed c-Si PV waste was distributed in the mixed powder, which was recycled by electrostatic separation. The effects of particle size of the powder, voltage of the DC power supply and rotation speed of the roller on the recovery of Si were investigated. The optimum particle size for recycling Si by electrostatic separation was 0.30–0.45 mm, and the best separation effect was achieved at a rotation speed of 30 rpm and a voltage of 15 kV at this particle size, with a Si proportion of 91.0% and a Si recovery rate of 48.9%. This study provides a new option for recycling Si from waste c-Si PV panels, which has a greater potential for industrial recycle.