| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which a crystal of a ferric alkali polyamino-polycarboxylate can economically be obtained in high yield and high purity with a small amount of waste liquors discharged and a slight environmental load according to simple operation. SOLUTION: The method for producing the ferric alkali polyamino-polycarboxylate is carried out by reacting a polyamino-polycarboxylic acid with an alkali and an iron compound in an aqueous solution, then carrying out an oxidizing treatment with molecular oxygen, concentrating the resultant aqueous solution of the ferric alkali polyamino-polycarboxylate, depositing the crystal of the salt so that the slurry concentration is 40-65 mass% and separating and recovering the crystal from the mother liquor. In the method, a part or all of the separated and recovered mother liquor is recycled and used for production after the next time. COPYRIGHT: (C)2007,JPO&INPIT
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