| 摘要 |
PROBLEM TO BE SOLVED: To obtain a common salt having mild deliciousness of natural salt and also decreased in deliquescence and caking property, to provide a method for producing the salt, and to provide a method for effectively utilizing seawater in association with the above method for producing the salt. SOLUTION: The bittern-containing common salt grains are such ones as to have cores of bittern-containing compositions which may contain NaCl; wherein the core surface is coated with a coating layer made of an NaCl-containing composition which may contain CaSO4 or bittern. A method for fractionating seawater into freshwater, an NaCl-containing composition and a bittern-containing composition and collecting the resultant water and compositions comprises either a process of fractionating seawater into freshwater and salt-containing water by reverse osmosis membrane treatment followed by fractionating the salt-containing water into NaCl-containing composition and bittern-containing composition by ion-exchange treatment, or process of fractionating seawater into NaCl-containing aqueous solution and bittern-containing aqueous solution by ion-exchange treatment followed by fractionating the NaCl- containing aqueous solution and bittern-containing aqueous solution into freshwater, NaCl-containing composition, and bittern-containing composition each by reverse osmosis membrane treatment. |
