A process for the recycling of high purity silicon metal

Abstract

A process for the re-use of remainders or other residual Si of high purity silicon such as saw dust or kerf from manufacturing of solar cells wafers or semi-conductor devices, is characterized in that the dry kerf, chips and/or other residual Si from wafer production processes or semi-conductor devices is used as feedstock together with metallurgical grade silicon in a direct chlorination reactor (1) producing silicon tetrachloride, SiCl4. Unreacted kerf or other small particles that escape the reaction zone unreacted are repeatedly returned to the reactor for further chlorination regardless of their size. The equipment included in the process may, beyond the reactor (1), comprise a storage and mixing device (2) for the mixing and storage of the Si material/kerf, a recovery device (3) for separation and recovery of Si containing particles escaping the reaction zone of the reactor and being returned to the reaction zone of the reactor by a return feeding means (9), a condensation unit (10) in which the smallest sized particles escaping the reaction zone of the reactor and recovery device are collected in a slurry with the liquid SiCl4, and a mixing unit (13) into which additional kerf, chips and other residual Si from wafer production processes or semi-conductor devices is added and mixed with the existing SiCl4/Si slurry that is subsequently added directly to the reaction zone of the reactor for cooling and temperature control.

Dependencies are inferred from the claim text.