title: Crystallization control for remediation of an FetO-rich CaO-SiO2-Al2O3-MgO EAF waste slag.
abstract: In this work, the crystallization behavior of synthesized FetO-rich electric arc furnace (EAF) waste slags with a basicity range of 0.7 to 1.08 was investigated. Crystal growth in the melts was observed in situ using a confocal laser scanning microscope, and a delayed crystallization for higher-basicity samples was observed in the continuous cooling transformation and time temperature transformation diagrams. This result is likely due to the polymerization of the melt structure as a result of the increased number of network-forming FeO4 and AlO4 units, as suggested by Raman analysis. The complex incorporation of Al and Fe ions in the form of AlO4 and FeO4 tetrahedral units dominant in the melt structure at a higher basicity constrained the precipitation of a magnetic, nonstoichiometric, and Fe-rich MgAlFeO4 primary phase. The growth of this spinel phase caused a clear compositional separation from amorphous phase during isothermal cooling at 1473 K leading to a clear separation between the primary and amorphous phases, allowing an efficient magnetic separation of Fe compounds from the slag for effective remediation and recycling of synthesized EAF waste slags for use in higher value-added ordinary Portland cement.
authors.affiliation: Department of Materials Science and Engineering, Yonsei University , Seoul 120-749, South Korea.
authors.forename: Sung Suk
authors.initials: SS
authors.lastname: Jung
authors.forename: Il
authors.initials: I
authors.lastname: Sohn
mesh_terms: D000537:Aluminum Oxide; D003460:Crystallization; D004055:Differential Thermal Analysis; D004560:Electricity; D007220:Industrial Waste; D008277:Magnesium Oxide; D018613:Microscopy, Confocal; D010087:Oxides / Q000737:chemistry*; D059027:Recycling; D012822:Silicon Dioxide; D013059:Spectrum Analysis, Raman; D013696:Temperature; D018505:Waste Management; D014961:X-Ray Diffraction
chemical_list: D007220:Industrial Waste; D010087:Oxides; C111130:spinell; D008277:Magnesium Oxide; D012822:Silicon Dioxide; D000537:Aluminum Oxide