Recovery of silicon from silicon sludge using supercritical water

Akira Yoko, Yoshito Oshima

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)1-5
Number of pages5
JournalJournal of Supercritical Fluids
Volume75
DOIs
Publication statusPublished - 2013 Mar
Externally publishedYes

Keywords

  • Elutriation
  • Recovery
  • Semi-batch reactor
  • Silicon sludge
  • Supercritical water

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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