Recovery of silicon from silicon sludge using supercritical water

Akira Yoko, Yoshito Oshima

研究成果: Article査読

35 被引用数 (Scopus)


In this paper, we propose a new methodology for recovering silicon from silicon sludge using supercritical water in a semi-batch reactor. Silicon sludge is the waste discharged from the silicon ingot cutting process and consists of cutting oil, cooling water, and silicon particles. The oil contained in silicon sludge was removed completely within several minutes by supercritical water elutriation at 400 or 500 °C and 25 MPa. The recovery percentage of silicon was only 70% at 400 °C owing to silicon dissolution. However, the recovery percentage was greater at a higher temperature (95% at 500 °C) because silicon dissolution was suppressed owing to the low ion product of water at higher temperatures. The silicon recovered at 500 °C and 25 MPa was approximately 99.2% pure. Contamination by oxidation was negligible because an oxide film did not grow on the silicon surface during the supercritical water treatment. We conclude that high-purity silicon can be recovered efficiently by supercritical water elutriation using a semi-batch reactor and that the methodology is promising for recovery of silicon from silicon sludge.

ジャーナルJournal of Supercritical Fluids
出版ステータスPublished - 2013 3

ASJC Scopus subject areas

  • 化学工学(全般)
  • 凝縮系物理学
  • 物理化学および理論化学


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