title: Fractionation and leachability of heavy metals from aged and recent Zn metallurgical leach residues from the Três Marias zinc plant (Minas Gerais, Brazil).
abstract: Various mineral processing operations to produce pure metals from mineral ores generate sludges, residues, and other unwanted by-products/wastes. As a general practice, these wastes are either stored in a reservoir or disposed in the surrounding of mining/smelting areas, which might cause adverse environmental impacts. Therefore, it is important to understand the various characteristics like heavy metal leaching features and potential toxicity of these metallurgical wastes. In this study, zinc plant leach residues (ZLRs) were collected from a currently operating Zn metallurgical industry located in Minas Gerais (Brazil) and investigated for their potential toxicity, fractionation, and leachability. Three different ZLR samples (ZLR1, ZLR2, and ZLR3) were collected, based on their age of production and deposition. They mainly consisted of Fe (6-11.5 %), Zn (2.5 to 5.0 %), and Pb (1.5 to 2.5 %) and minor concentrations of Al, Cd, Cu, and Mn, depending on the sample age. Toxicity Characteristic Leaching Procedure (TCLP) results revealed that these wastes are hazardous for the environment. Accelerated Community Bureau of Reference (BCR) sequential extraction clearly showed that potentially toxic heavy metals such as Cd, Cu, Pb, and Zn can be released into the environment in high quantities under mild acidic conditions. The results of the liquid-solid partitioning as a function of pH showed that pH plays an important role in the leachability of metals from these residues. At low pH (pH 2.5), high concentrations of metals can be leached: 67, 25, and 7 % of Zn can be leached from leach residues ZLR1, ZLR2, and ZLR3, respectively. The release of metals decreased with increasing pH. Geochemical modeling of the pH-dependent leaching was also performed to determine which geochemical process controls the leachability/solubility of the heavy metals. This study showed that the studied ZLRs contain significant concentrations of non-residual extractable fractions of Zn and can be seen as a potential secondary resource for Zn.
authors.affiliation: Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est, EA 4508, UPEM, 77454, Marne-la-Vallée, France. biotek_mani@yahoo.co.in.|Department of Environmental Engineering and Water Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX, Delft, The Netherlands. biotek_mani@yahoo.co.in.|NGqA-CPMTC, Instituto de Geociências, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31270-901, Brazil. biotek_mani@yahoo.co.in.
authors.forename: Manivannan
authors.identifier: http://orcid.org/0000-0002-2608-9424
authors.initials: M
authors.lastname: Sethurajan
authors.affiliation: Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est, EA 4508, UPEM, 77454, Marne-la-Vallée, France.
authors.forename: David
authors.initials: D
authors.lastname: Huguenot
authors.affiliation: Department of Environmental Engineering and Water Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX, Delft, The Netherlands.
authors.forename: Piet N L
authors.initials: PN
authors.lastname: Lens
authors.affiliation: NGqA-CPMTC, Instituto de Geociências, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
authors.forename: Heinrich A
authors.initials: HA
authors.lastname: Horn
authors.affiliation: Solos e nutrição de plantas, Universidade Estadual de Montes Claros, Avenida Reinaldo Viana, 2630, Bico da Pedra, Janauba, MG, 39440-000, Brazil.
authors.forename: Luiz H A
authors.initials: LH
authors.lastname: Figueiredo
authors.affiliation: Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est, EA 4508, UPEM, 77454, Marne-la-Vallée, France. Eric.vanHullebusch@univ-mlv.fr.
authors.forename: Eric D
authors.initials: ED
authors.lastname: van Hullebusch
mesh_terms: D001938:Brazil; D004784:Environmental Monitoring / Q000331:legislation & jurisprudence / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D008669:Metallurgy; D019216:Metals, Heavy / Q000032:analysis* / Q000633:toxicity; D008906:Mining; D008962:Models, Theoretical; D012995:Solubility; D013997:Time Factors; D015032:Zinc / Q000032:analysis* / Q000633:toxicity
chemical_list: D004785:Environmental Pollutants; D007220:Industrial Waste; D019216:Metals, Heavy; D015032:Zinc
keywords: Geochemical modeling; Metal fractionation; TCLP; Zinc plant leach residues; pH stat leaching