<報文>都市廃棄物の処理と資源化に関する基礎的研究(III) : 電気集じん灰の鉄共沈セメント固化処理

概要

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A new cementation process has been developed for safe disposal of electric-precipitator dust (E.P.Dust) which contains several elements such as Zn, Cd, Pb, Cu, Hg, Cr and As. The major components of E.P.Dust are NaCl, KCl and glaserite, K_3Na(SO_4)_2 which seriouslv retards the solidification of cement when mixed with E.P.Dust. In order to overcome this problem, we propose a new process using coprecipitation reaction of Fe(OH)_2. The process consists of the following three stages : 1) E.P.Dust is dissolved in ferrous sulfate aqueous solution and stirred with Ca(OH)_2 milk. 2) The slurry consists of ferrous hydroxide which occuldes heavy metal ions is dehydrated by conventional filter press. 3) The dehydrated cakes are mixed with Portland cement and pelletized. The solidified product containing ferrous hydroxide as the additive has the following advantages when compared with the conventional cementation products in which E.P.Dust is mixed directly with Portland cement : 1) Excellent compressive strength 2) Good prevention of heavy metal ion leakage even under weak acidic environment 3) Stable form-preventability in water The advantages of this solidification process are removal of salts which interfere in cementation reaction and formation of solid solution between heavy metal ions and ferrous ions. Futhermore, the mechanism of immobilization of chromate ions is discussed from the view point of solution chemistry.
東北大学の論文
1984-09-25