To provide a method for producing polycrystalline silicon whose production cost is low and operation control and apparatus control are simple.
The method for producing high purity polycrystalline silicon includes oxidation treatment which oxidizes a mixture of the zinc chloride which is separated from a discharge gas formed by a reaction of high purity silicon tetrachloride and zinc and unreacted zinc, aqueous hydrochloric acid solution dissolution treatment which dissolves the mixture in an aqueous hydrochloric acid solution, zinc component extraction treatment which extracts zinc component by an acidic extractant, zinc component back-extraction treatment which back-extracts the zinc component by an aqueous sulfuric acid solution, aqueous zinc sulfate solution electrolytic treatment which carries out aqueous solution electrolysis of the aqueous zinc sulfate solution, hydrochloric acid purification treatment which purifies a part of the aqueous hydrochloric acid solution obtained by the zinc component extraction treatment and hydrogen chloride vaporization treatment which vaporizes hydrogen chloride gas, or hydrogen chloride vaporization purification treatment which vaporizes a part of aqueous hydrochloric acid solution obtained by the zinc component extraction treatment and purifies hydrogen chloride, and carries out cyclic use of other parts of the aqueous hydrochloric acid solution, an organic solvent containing the acid extractant and the aqueous sulfuric acid solution.
MUNAKATA HIROSHI
DODA MASAHIKO
Yasuyuki Sakata
Ken Shibuya
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