title: Effects of thin-film accelerated carbonation on steel slag leaching.
abstract: This paper discusses the effects of accelerated carbonation on the leaching behaviour of two types of stainless steel slags (electric arc furnace and argon oxygen decarburisation slag). The release of major elements and toxic metals both at the natural pH and at varying pH conditions was addressed. Geochemical modelling of the eluates was used to theoretically describe leaching and derive information about mineralogical changes induced by carbonation. Among the investigated elements, Ca and Si were most appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed for silicate phases; geochemical modelling indicated that the Ca/Si ratio of Ca-controlling minerals shifted from ∼ 1 for the untreated slag to 0.5-0.67 for the carbonated samples, thus showing that the carbonation process left some residual Ca-depleted silicate phases while the extracted Ca precipitated in the form of carbonate minerals. For toxic metals the changes in leaching induced by carbonation appeared to be mainly related to the resulting pH changes, which were as high as ∼ 2 orders of magnitude upon carbonation. Depending on the specific shape of the respective solubility curves, the extent of leaching of toxic metals from the slag was differently affected by carbonation.
authors.affiliation: Laboratory of Environmental Engineering, University of Rome "Tor Vergata", Via del Politecnico 1 - 00133 Rome, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Baciocchi
authors.affiliation: Laboratory of Environmental Engineering, University of Rome "Tor Vergata", Via del Politecnico 1 - 00133 Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Costa
authors.affiliation: Department of Civil and Environmental Engineering, University of Rome "La Sapienza", Via Eudossiana 18 - 00184 Rome, Italy. Electronic address: alessandra.polettini@uniroma1.it.
authors.forename: A
authors.initials: A
authors.lastname: Polettini
authors.affiliation: Department of Civil and Environmental Engineering, University of Rome "La Sapienza", Via Eudossiana 18 - 00184 Rome, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Pomi
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D057965:Carbon Sequestration; D007220:Industrial Waste / Q000032:analysis*; D008670:Metals / Q000032:analysis*; D008962:Models, Theoretical; D013193:Stainless Steel; D018505:Waste Management / Q000379:methods*
chemical_list: D007220:Industrial Waste; D008670:Metals; D013193:Stainless Steel; D002245:Carbon Dioxide
keywords: Accelerated carbonation; CO(2) sequestration; Metal leaching; Steel slag