| 摘要 |
PROBLEM TO BE SOLVED: To carry out complete solidification of heavy metals within a short period of time by adding water and an aluminum salt to soil contaminated with heavy metals and stirring the resulting soil to insolubilize the heavy metals contained in the soil. SOLUTION: In order to make soil in a site of a factory which is contaminated with heavy metals completely harmless, the contaminated soil which has been granulated to have specified grain sizes is charged into a mixer, then aluminum sulfate as a trivalent aluminum salt and water are added thereto and both are blended and uniformly dispersed so as to form a wet state. Because the mixture thus obtained is acidic, slaked lime is added to and stirred with the mixture to adjust pH to 7-12, preferably 7.5-11.5. The trivalent aluminum reacts with the heavy metals and is subjected to oxidation by air during the process of mixing to gradually form crystal lattices of aluminum oxides, and in this process aluminate based composite oxides having spinel crystal structures are gradually formed. Aluminum hydroxide, alum and the like can be used as the trivalent aluminum salt. |
