| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing an iron-aluminum combined flocculant strong in flocculating action and high in concentration and preservation stability at a low cost. SOLUTION: An iron-aluminum combined body, which is contained in the iron-aluminum combined flocculant and has 3 or lower iron/aluminum ratio in terms of Fe2O3/Al2O3, is manufactured by the first step to precipitate iron- aluminum multiple hydroxide or aluminum hydroxide by reacting an aqueous solution of iron salt and/or aluminum salt with an aqueous solution of aluminate of an alkali metal at 20 deg.C or lower and the second step to dissolve the iron- aluminum multiple hydroxide by acidifying the reaction system by adding an acidic material and heating the system. The aqueous solution of iron salt and/or aluminum salt is used as the acidic material.
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