| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for restraining a formation of an alkali insoluble compound and increasing a recovery ratio of reusable aluminum and a device, in a treatment of sludge incorporating an aluminum compound generating at a fluorine-containing waste water treatment. SOLUTION: In this method, carbonate salt more than an equivalent of ionic calcium contained in the sludge is charged to the sludge before an aluminum extraction process from the sludge. The sludge is adjusted to pH from >=8 to <=9.5, then is allowed to react. The sludge in the extraction process of aluminum is adjusted to pH from >=10 to <=12.5.
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