| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus with an aim of recovering a crystal having a quality capable of being supplied to an electrolytic apparatus for producing a caustic alkali and chlorine from a mixed salt crystal of sodium chloride and potassium chloride yielded by evaporating and concentrating various waste liquids. SOLUTION: Sodium chloride with a less content of potassium chloride is recovered by adding a mixed salt containing sodium chloride as a major component and potassium chloride of≥1% yielded from an evaporation, concentration, and crystallization process of various waste liquids to a circulating mother liquid kept near a eutectic point of sodium chloride and potassium chloride, selectively dissolving potassium chloride contained in the mixed salt by heating, and centrifugally separating with addition of water. A potassium chloride crystal containing sodium chloride of≤1% is separated by cooling the centrifugally separated filtrate, depositing a potassium chloride crystal, and centrifugally separating while adding water. COPYRIGHT: (C)2006,JPO&NCIPI
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