Potential Routes for Recycling and Reuse of Silicon Kerf

Abstract

In photovoltaic industry during wafer sawing significant amount of solar grade silicon is getting lost into sawing slurry. In the present paper, potential approach and routes for recycling and reuse of silicon wafer sawing slurry are explored. Various techniques were used including distillation, heavy liquid separation, acid leaching and high temperature processing. After distillation, the polyethylene glycol (PEG) can be separated and reused as lubricant. By dissolving silicon at high temperatures from the kerf into a clean molten pool of silicon metal or scrap, or into an alloying metal like Cu, SiC can also be separated and recovered. Depending on the impurity level, solar grade silicon can be finally produced from this waste stream in combination with necessary refining treatment for the applications in the PV industry. Furthermore, converting the kerf into SiC or Si3N4 particles as technical ceramic products is also explored. It is expected that the present research can pave a way to develop a total recycling route for an optimum use of this resource, and to minimize the environmental risk of the waste disposal.