Effects of thin-film accelerated carbonation on steel slag leaching

This paper discusses the effects of accelerated carbonation on the leaching behaviour of two types ofstainless steel slags (electric arc furnace and argon oxygen decarburisation slag). The release of majorelements and toxic metals both at the natural pH and at varying pH conditions was addressed. Geo-chemical modelling of the eluates was used to theoretically describe leaching and derive informationabout mineralogical changes induced by carbonation. Among the investigated elements, Ca and Si weremost appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed forsilicate phases; geochemical modelling indicated that the Ca/Si ratio of Ca-controlling minerals shiftedfrom ∼1 for the untreated slag to 0.5–0.67 for the carbonated samples, thus showing that the carbon-ation process left some residual Ca-depleted silicate phases while the extracted Ca precipitated in theform of carbonate minerals. For toxic metals the changes in leaching induced by carbon