To provide a method for insolubilizing an ash containing heavy metals for insolubilizing heavy metals in the ash containing heavy metals and preventing its elution easily, efficiently at a low cost so as to satisfy the soil environmental standard in an elution test and acidic condition by the Notification no. 46 for the Soil pollution environmental standard.
In the method, a solution of a bivalent iron compound or a trivalent iron compound and a thiosulfate compound is added to the ash containing heavy metals and mixed therewith, then, the ash containing heavy metals is heated. For example, ferrous sulfate forms arsenic acid ion, arsenious acid ion, selenic acid ion, and selenious acid ion which are an elution form of arsenic and selen, and a refractory compound, then insolubilizes them. The thiosulfate compound reduces all the selenic acid ion and selenious acid ion which are the elution form of selen by sulfur dioxide and hydrogen sulfide generated by thermolysis to the form of selenious acid ion forming the refractory compound by the ferrous sulfate or reduces it up to 0-valent selen which is an insoluble body as it is, thereby the elution of selen is suppressed.
COPYRIGHT: (C)2004,JPO
Naofumi Nomura
Tatsuya Sakamoto
Yoshitaka Sugiyama
Kiyoaki Kitamura
Tokyo
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Yoshihiro Morimoto
Toshiji Sasahara
Yohei Harada