A sustainable mineral process for silicon and quartz recovery from quartz crucible waste ash via electrical separation

Driven by the explosive development of the photovoltaic (PV) industry, the treatment of the quartz crucible waste ash (QCWA) from monocrystalline silicon rod production must be considered to combat the shortage of silicon materials and promote sustainable development. In particular, the loss of grade 4 N high-purity silicon in QCWA is a frustrating fact for the silicon supply chain. In this work, an electrical separation process is proposed for the recovery of silicon and quartz from QCWA to realize waste resource reutilization. The charging processes and forces in the feed QCWA are first analyzed. Then, the electric field distribution during electrical separation is simulated to clarify the movement models of silicon and quartz particles and formulate reasonable electrical separation parameters. After systematic theoretical analysis, calculation, and simulation, electrical separation experiments were conducted. The results prove that the content of silicon in the concentrate and the corresponding content of quartz in the tailing respectively exceeded 93 % and 61 % under a particle size of 80 ∼ 120 mesh, a voltage of 40 kV, and a roll speed of 75 r/min. This work demonstrates that electrical separation is a sustainable process that could be recommended for silicon and quartz recovery from QCWA.