| 摘要 |
PURPOSE:To enable ash containing heavy metals including incineration ash from municipal waste, industrial waste, etc., to be made harmless over a long period of time by adding water, acid, and bivalent iron to the ash and heating the agitated mixture. CONSTITUTION:In the treatment to make ash containing heavy metals harmless, water, acid, and bivalent iron are added to the ash. Since the heavy metals contained in waste are dissolved into water added for kneading, the wet mixture is incorporated with an acid such as sulfuric acid or hydrochloric acid and a bivalent iron compound such as ferrous sulfate or ferrous chloride so that they are dispersed uniformly. The mixture, after being adjusted of its pH to 7.0-11.5, is kept at 50-95 deg.C, so that bivalent iron in the mixture is gradually converted into ferrite by crystallization. In the process in which the crystal lattice of the ferrite is formed by the bivalent iron atoms, other heavy metal atoms are caught to be fixed in place of the iron atoms in the positions which are to be occupied by the iron atoms. |
