Abstract
The removal of metal impurities is essential when recycling silicon sawing waste. In this study, Si, SiC, and metal fragments were separated by sedimentation in an applied electrical field. A magnetic field was incorporated into the system to promote the separation of iron-based fragments from the sawing waste. When a 1 V/cm electrical field and a 0.3 T magnetic field were applied for 24 h to the system in a pH7 solution, the residual amount of iron reduced to less than 0.0185% of the initial amount. The maximum SiC content in the recovered powder was 87.8 wt%, while the minimum was 12.3 wt%, i.e., roughly 87.7 wt% Si. Applying a magnetic field to the recycling system can effectively reduce the residual iron content; in addition, Si, SiC, and metal fragments can be separated in a single procedure.
ACKNOWLEDGEMENTS
The author would like to thank the National Science Council of Taiwan for financially supporting this research under Contract No. NSC 99-2221-E-027-099-MY2, and thank Yung-Fu Wu of Electrochemical engineering lab II (Ming-Chi University of Technology) for assistance in separation tank design and system construction. The material support from Sino-American Silicon Products, Inc. is also greatly acknowledged.
Notes
a Residual fraction: the residual amount of iron divided by the initial amount.
b B: magnetic field.