Silicon recovery from cutting slurry by phase transfer separation

The cost of silicon feedstock is one of the most important factors for photovoltaic (PV) energy to reach grid parity. However, about 40% of high-purity silicon has been wasted as kerf loss during slicing. In the past decade, the recycle of silicon from the kerf-loss slurry waste has attracted much attention, but the progress is very slow. One of the technological challenges is the separation of SiC and Si particles. In this paper, a phase-transfer method using diesel based on the hydrophobicity difference between Si and SiC was proposed. SiC particles were enriched in the emulsion phase due to their more hydrophobic nature than Si. Si powder with a purity of 95 wt% could be obtained, and the yield was about 80%. The factors, such as emulsification, affecting the separation efficiency were further discussed.