| 摘要 |
PURPOSE:To obtain silicon having high purity efficiently and economically with a simplified process by allowing SiO2 which has been preheated separately to specified temps. to contact with a reducing agent in a reaction furnace. CONSTITUTION:SiO2 (A) pulverized to ca.50-350 mesh particle size is fed to a first heating furnace 11 from a hopper 51 and preheated by plasma jet generated by a plasma torch 61 to >=1,900 deg.C. On one hand, a reducing agent B (e.g. active carbon) is fed from a hopper 52 to a second heating furnace 12 and preheated at >=1,900 deg.C by the plasma jet generated by a plasma torch 62. Then, both are fed to a reaction furnace 21 through connecting pipes 31, 32 held at >=1,900 deg.C by heating with heaters 41, 42 provided around the connecting pipes. SiO2 (A) and the reducing agent B are heated at >=1,900 deg.C by the arc plasma generated by an arc generating electrode 71 and are allowed to contact to reduce the SiO2 completely to Si, which is recovered into a vessel 81.
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