| 摘要 |
PURPOSE:Metallic silicon, as starting substance, is melted at elevated temperatures and recrystallized, then the size of the crystals is allowed to grow up and finally the crystals are acid-treated whereby effective acid treatment becomes possible to give high-purity metallic silicon. CONSTITUTION:Metallic silicon of more than 98wt% purity is crushed into particles of preferably less than 10mm. size and melted at a temperature higher than 1,420 deg.C, the melting point of silicon to effect complete melting. Then, the melt is kept near the solidifying point from more than 1hr and cooled down gradually to form solidified product of more than 5mm. crystal size. The product is crushed into a powder of less than 1mm. particle size and treated with hydrofluoric acid or a mixture thereof with hydrochloric acid to remove impurities. The resultant metallic silicon can be used as a starting material for making high-purity silicon ceramic and as a substituent for vapor-phase metallic silicon which has been used in solar cells.
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