Recovery of high purity silicon from SoG crystalline silicon cutting slurry waste

The recovery of high-purity Si from the cutting slurry waste of SoG-Si was investigated. The composition and size distribution of cutting waste were characterized. The Si-rich powders were obtained from the cutting waste using a physical sedimentation process, and then further purified by removing impurity using acid leaching. The effects of process parameters such as acid leaching time, temperature and the ratio of solid to liquid on the purification efficiency were investigated, and the parameters were optimized. Afterwards, the high-purity Si ingot was obtained by melting the Si-rich powders in vacuum furnace. Finally, the high purity Si with 99.96% Si, 1.1×10−6 boron (B), and 4.0×10−6 phosphorus (P) were obtained. The results indicate that it is feasible to extract high-purity Si, and further produce SoG-Si from the cutting slurry waste.