title: Optimisation of magnetic separation: a case study for soil washing at a heavy metals polluted site.
abstract: Sandy loam soil polluted with heavy metals (As, Cu, Pb and Zn) from an ancient Mediterranean Pb mining and metallurgy site was treated by means of wet high-intensity magnetic separation to remove some of the pollutants therein. The treated fractions were chemically analysed and then subjected to magnetic characterisation, which determined the high-field specific (mass), magnetic susceptibility (κ) and the specific (mass) saturation magnetisation (σS), through isothermal remanent magnetisation (IRM) curves. From the specific values of κ and σS, a new expression to assess the performance of the magnetic separation operation was formulated and verified by comparison with the results obtained by traditional chemical analysis. The magnetic study provided valuable information for the exhaustive explanation of the operation, and the deduced mathematical expression was found to be appropriate to estimate the performance of the separation operation. From these results we determined that magnetic soil washing was effective for the treatment of the contaminated soil, concentrating the majority of the heavy metals and peaking its separation capacity at 60% of the maximum output voltage.
authors.affiliation: Environmental Biotechnology and Geochemistry Group, University of Oviedo, C/Gonzalo Gut. s/n, 33600 Mieres, Asturias, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Sierra
authors.affiliation: Servicio Científico-Técnico de Medidas Magnéticas, University of Oviedo, C/Gonzalo Gut. s/n, 33600 Mieres, Asturias, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Martínez-Blanco
authors.affiliation: Departamento de Física, University of Oviedo, C/Calvo Sotelo s/n, 33007 Oviedo, Spain.
authors.forename: Jesús A
authors.initials: JA
authors.lastname: Blanco
authors.affiliation: Environmental Biotechnology and Geochemistry Group, University of Oviedo, C/Gonzalo Gut. s/n, 33600 Mieres, Asturias, Spain. Electronic address: jgallego@uniovi.es.
authors.forename: J R
authors.initials: JR
authors.lastname: Gallego
mesh_terms: D005240:Feasibility Studies; D060328:Magnetic Phenomena; D008669:Metallurgy; D019216:Metals, Heavy / Q000032:analysis / Q000302:isolation & purification*; D008906:Mining; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000302:isolation & purification*
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants
keywords: Magnetic separation; Mineral processing; Soil contamination; Soil washing