| 摘要 |
<p>PURPOSE:To make the stable treatment of fluorine possible, by injecting an Al compound in the cooling step of exhaust gas to form a fluorine-Al complex body by the decomposition of a borofluoride in waste water, adding a Ca compound to the waste water, and then separating precipitated calcium fluoride from it. CONSTITUTION:An Al compound such as aluminum hydroxide is injected in the step of cooling exhaust gas to form a fluorine-Al complex body by the decomposition of a borofluoride contained in waste water in said cooling step, a Ca compound such as slaked lime is then added to the waste water in the cooling step to adjust a pH to 7-9, and precipitated calcium fluoride is separated therefrom. The addition amount of said Al compound is determined in a manner such that the molar ratio of soluble Al to fluorine in the waste water in the cooling step after the addition of the Al compound exceeds 0.4. As a result, the stable effect to treat waste water holding fluorine content in treated water at below 15mg/l is obtained.</p> |
