| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of efficiently producing a high-purity silicon low in impurities for a solar battery with one time of solidification and purification. SOLUTION: Silicon oxide is reduced with carbon to obtain metallic silicon. Metallic silicon is smelted by oxidation, roughly purified by solidification, vacuum-smelted and finish-purified by solidification so that the silicon for a solar battery is produced. In this case, the carbon-reduced molten metallic silicon is injected directly into a mold 1 with >=0.2 height/equivalent diameter (d) ratio, slowly cooled while heating or heat-keeping the molten silicon surface 5 and solidified, and then the solidified material 6 is purified without being subjected to rough purification by solidification. The equivalent diameter is made to be defined by d=√(cross-sectional area×4/π).
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