Recycling of kerf loss silicon: An optimized method to realize effective elimination of various impurities

Photovoltaic solid waste, particularly diamond-wire sawing silicon powder (DWSSP), has emerged as a significant concern in the industry. Consequently, the recycling and reuse of such waste have become a prominent research focus. In this study, focusing on achieving direct recycling and reuse of DWSSP, the key driving factors for effective purification were identified. It was found that simply increasing the melting temperature and time was insufficient to completely remove volatile impurities, and the migration process in the melt had to be taken into consideration. Additionally, this study focused on analyzing the instability model of inter-granular grain growth and its impact on the stable migration of impurities, with particular attention to the microstructure of inter-granular micro-regions. The thermal control directional solidification technique focused on controlling the temperature gradient during the melt solidification process. This approach helped stabilize the microstructure, enhance impurity migration, and ultimately led to a more effective purification of DWSSP.