Metal removal from silicon sawing waste using the electrokinetic method

Silicon feedstock supply for the photovoltaic industry can be increased by recycling sawing waste. Metal removal is an important step in recycling silicon from sawing waste. This study examined the feasibility of adopting the electrokinetic method to remove metal from sawing waste. Exactly how an applied electrical field and its duration affect metal removal efficiency was studied. The optimal operational parameters were analyzed based on a cost model. Analytical results show that metal removal depends on proton generation, adsorption exchange and electromigration. Increasing the electrical field and duration can reduce the residual iron in the kerf-loss slurry. When an electrical field of 2.0 V/cm was applied for 120 h, total residual iron percentage decreased to 0.42 wt.% in the slurry, and total removal efficiency was at least 92%. The local removal efficiency of iron could reach 98%. (c) 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.