title: Thin-film versus slurry-phase carbonation of steel slag: CO₂ uptake and effects on mineralogy.
abstract: The results of direct aqueous accelerated carbonation of three types of steel manufacturing residues, including an electric arc furnace (EAF) slag and two basic oxygen furnace (BOF) slags, are reported. Batch accelerated carbonation tests were conducted at different temperatures and CO2 pressures applying the thin-film route (liquid to solid, L/S, ratio=0.3L/kg) or the slurry-phase route (L/S ratio=5L/kg). The CO2 uptake strongly depended on both the slag characteristics and the process route; maximum yields of 280 (EAF), 325 (BOF1) and 403 (BOF2) gCO2/kg slag were achieved in slurry phase at T=100°C and pCO2=10 bar. Differently from previous studies, additional carbonates (other than Ca-based phases) were retrieved in the carbonated BOF slags, indicating that also Mg-, Fe- and Mn-containing phases partially reacted with CO2 under the tested conditions. The results hence show that the effects of accelerated carbonation in terms of CO2 uptake capacity, yield of mineral conversion into carbonates and mineralogy of the treated product, strongly rely on several factors. These include, above all, the mineralogy of the original material and the operating conditions adopted, which thus need specific case-by-case optimization to maximize the CO2 sequestration yield.
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science 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, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Costa
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Gianfilippo
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
authors.affiliation: Department of Civil and Environmental Engineering, University of Rome "La Sapienza", Via Eudossiana 18, 00184 Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Stramazzo
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D002254:Carbonates; D007220:Industrial Waste; D012037:Refuse Disposal / Q000379:methods*; D013232:Steel
chemical_list: D002254:Carbonates; D007220:Industrial Waste; D013232:Steel; D002245:Carbon Dioxide
keywords: Accelerated carbonation; CO(2) uptake; Conversion yield; Mineralogical characterization; Steel slag