A process for the preparation of sawing waste dispersion for the recovery of silicon for the production of solar silicon

The invention relates to a method for the treatment of sawing waste dispersion for the recovery of solar grade silicon for the production of solar cells. For the production of silicon wafers, the silicon blocks are cut with the wire saw into wafers having an average thickness of about 180 micrometers. Here, about 45% of the expensive raw material to be machined off and washed into the slurry of it. In the inventive method, the solid components of the sawing waste that silicon levels with the required purity have formed into granules of suitable size and then accommodated in a reaction vessel with Clorwasserstoff in reaction, so that there arise trichlorosilane and silicon tetrachloride and the iron components of the sawing waste converted into iron chloride while the contained SiC shares accumulate unchanged in the lower part of the reaction vessel as dust. The resulting reaction gases in the reaction vessel trichlorosilane and silicon tetrachloride separated in subsequent distillation steps and fed to the silicon manufacturing process again. The process may be carried out as a fluidized bed process in a fluidized bed furnace, wherein the grain size of the granules is in a range of a few hundred micrometers, and the conversion process is carried out at temperatures of about 350 ° C. The method may alternatively be carried out in a shaft furnace, wherein the grain size of the granules in a range ...