Source of boron and phosphorus impurities in the silicon wiresawing slurry and their removal by acid leaching

The B and P were often found in the waste wiresawing slurry, and their complete removal is very significant to the effective recycling of silicon scrap for solar energy cell. The source of them was confirmed from the steel wire used as the cutting after systematical study. The cutting wires must be brass plated before drawing to proper diameter during the production. Surface treatment of steel wires contains phosphating and covering borax to improve the corrosion resistance and the drawing property. The wires were irrevocably scuffed after using, and the steel scraps will be mixed in the cutting slurries. This finding suggested that using an appropriated method instead of phosphating can avoid the introduction of B and P, and the subsequent procedure was simple and low in cost.240