method for separation and recovery of polyethylene glycol and silicon carbide abrasives for purposes of reuse

摘要

A method for treating an exhausted fluid used in a process for slicing monocrystalline silicon containing a particulate abrasive material and a suspending agent, and including their separation and their regeneration for re-use, as well as silicon powder residuals comprising the steps of : a) lowering the viscosity of the exhausted fluid by addition of water; b) separating a water suspension of the available abrasive particles and a water suspension containing the silicon powder; c) drying the suspension of said abrasive particles in a furnace for recovery and re-use thereof; and d) filtering said water suspension of silicon powder in order to recover the silicon powder for subsequently drying and possibly re-using it, characterized in that said abrasive material is silicon carbide and said suspending agent is polyethylene glycol (PEG) and in that it further comprises the following steps: i) before said water dilution step a), warming said exhausted abrasive fluid so as to lower its viscosity, ii) filtering said exhausted warmed lower viscosity fluid, in order to obtain, on one hand, a wet powder agglomerate consisting of silicon carbide particles and silicon powder, said agglomerate being then subjected to said a), b), c) and d) steps, and, on the other hand, said suspending agent (PEG) which contain silicon powder, iii) separating said suspending agent (PEG) so as to extract pure suspending agent (PEG) intended for re-use and separating said silicon powder traces, that can be subsequently disposed or possibly reused. IMAGE IMAGE IMAGE