Boron Removal in Molten Silicon with Steam Added Plasma Melting Method

Naomichi Nakamura, Hiroyuki Baba, Yasuhiko Sakaguchi, Shoichi Hiwasa, Yoshiei Katou

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Boron removal in molten silicon with a steam added plasma melting method was investigated as an important part of the sequential metallurgical process to produce highly purified solar grade silicon (SOG-Si) from commercially available metallurgical grade silicon (MG-Si). Experiments were carried out from laboratory to industrial scale and silicon amount used per charge was varied from 0.6 to 300 kg. Boron was stably removed to permissible boron content for SOG-Si of [B] <0.1 mass ppm. Deboronization rate was proportional to steam content, 3.23th power of hydrogen content in plasma gas, boron content in molten silicon and area of dimple formed by plasma gas jet, and inversely proportional to the mass of molten silicon. An application of the thermodynamics leads to preferential boron oxidation in molten silicon due to higher temperature, which showed that this plasma method capable of locally heightening the temperature of the reaction surface was advantageous in principle.

Original languageEnglish
Pages (from-to)583-589
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume67
Issue number10
Publication statusPublished - Oct 2003
Externally publishedYes

Fingerprint

Boron
Steam
Silicon
steam
Molten materials
boron
Melting
melting
Plasmas
silicon
Plasma Gases
grade
gas jets
Surface reactions
Gases
surface reactions
Hydrogen
Thermodynamics
Oxidation
Temperature

Keywords

  • Boron
  • Hydrogen
  • Metallurgical grade silicon
  • Photovoltaic cell
  • Plasma
  • Silicon
  • Solar grade silicon
  • Steam

ASJC Scopus subject areas

  • Metals and Alloys

Cite this

Boron Removal in Molten Silicon with Steam Added Plasma Melting Method. / Nakamura, Naomichi; Baba, Hiroyuki; Sakaguchi, Yasuhiko; Hiwasa, Shoichi; Katou, Yoshiei.

In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, Vol. 67, No. 10, 10.2003, p. 583-589.

Research output: Contribution to journalArticle

Nakamura, Naomichi ; Baba, Hiroyuki ; Sakaguchi, Yasuhiko ; Hiwasa, Shoichi ; Katou, Yoshiei. / Boron Removal in Molten Silicon with Steam Added Plasma Melting Method. In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals. 2003 ; Vol. 67, No. 10. pp. 583-589.
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