鉄鋼スラグの地盤材料としての有効利用に伴うフッ素の溶出挙動とその環境の評価

Abstract

産業廃棄物の地盤材料としての有効利用に関する研究は多数実施されており、主に力学的特性や安定性の改善、有害物資の溶出挙動の抑制を通して、利用用途の拡大が図られている。鉄鋼スラグについては、その有効利用率が高いものの、含有されるフッ素などの溶出が懸念されている。本研究では、複数の鉄鋼スラグを対象に各種溶出試験を行い、鉄鋼スラグからのフッ素、ﾎｳ素の溶出特性を評価した。さらに、地盤材料として鉄鋼スラグを有効利用した際のフッ素の溶出挙動について、数値解析を用いて定量的に評価し、環境リスクの観点からその環境安全性と適正な利用形態について議論を行った。

Leaching behaviors of inorganic chemicals in waste slag utilization as road base material were assessed based on results of laboratory leaching tests. Column leaching tests, as well as several batch leaching tests, were conducted to examine the fluoride and boron leaching from steel slag, influenced by the permeation velocity and the thickness of slag layer. Experimental results showed that fluoride leaching amount was significantly controlled by the permeaton velocity as well as the cumulative flow volume per unit weight of slag. Leaching behaviors from road base constructed with slag material were modeled using the advection-dispersion chemical transport analysis, considering the effect of flow volune on the leaching concentration. Analytical results confirmed that the environmental risk, coused by the fluoride leaching, resulted in the accepted level against the rain infiltration into the road base.