Centrifugal Separation of Primary Silicon during Solidification in Al-Si Alloy for Solar Silicon Feedstock

Abstract:

Various metallurgical refining processes of SOG (Solar Grade)-Si are being developed aiming its cost reduction for the PV (Photovoltaic) market. High purity silicon can also be obtained from Al-Si alloys using solidification theory. Since the solubility of impurity elements in silicon decreases rapidly with temperature decrease much above the Al-Si eutectic temperature, the removal of impurities from silicon at low temperature is expected to be effective. Most of impurity elements with small segregation coefficient can be removed during solidification. Key technology in this process is to separate the primary solid silicon from the liquid eutectic matrix during solidification. Some methods by an electromagnetic force or by combining flocculation and filtration techniques have been proposed to separate the solid silicon. The present study describes a new way to extract the primary silicon crystal from Al-Si alloys using centrifugal force during solidification for a silicon solar feedstock. Primary silicon was separated in the shape of foam during solidification, and pure Si flakes after acid leaching could be obtained.

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 819-822
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.819
• Online since: January 2012
• Authors: Ju Young Cho, Bok Hyun Kang, Ki Young Kim
• Keywords: Acid Leaching, Centrifugal Separation, Primary Silicon, Recovery, Refining, Solargrade Silicon (SOG-Si)

References

[1] A. M. Mitrašinović and Torstein A. Utigard : Silicon 1 (2009), pp.239-248.

[2] T. Koyama, M. Ikeda, Y. Shibuta and T. Suzuki : Tetsu-to-Hagané 94 (2008), pp.491-501.

[3] T. Yoshikawa and K. Morita : Journal of Crystal Growth 311 (2009), pp.776-779.

[4] T. Yoshikawa and K. Morita : ISIJ International 45 (2005), pp.967-971.

[5] D. Sollmann : Photon International (2009), pp.110-113.

[6] T. Yoshikawa and K. Morita : Journal of Crystal Growth 311. (2009), pp.776-779.