Recovery of silicon powder from kerf loss slurry by centrifugation

A feasibility study on recovering silicon powder from slurry containing silicon carbide abrasives, silicon kerfs, and iron fragments generated by slicing silicon ingots in the wire-saw process was conducted. The glycol solution and iron fragments in the slurry were removed using acetone and nitric acid, respectively. Then, centrifugation was applied to separate the silicon kerfs and silicon carbide abrasives using a heavy-liquid with a density between that of silicon and silicon carbide. The effects of several operational variables on the purity and yield of silicon kerfs were systematically investigated, including solid volume fraction, heavy-liquid density, number of centrifugation steps, and centrifugation time. Additionally, the effects of agitation for dispersing particles in the heavy-liquid before centrifugation were also studied. The purity and yield of Si product at specified conditions are reported. (C) 2010 Elsevier B.V. All rights reserved.