title: Leaching of potential hazardous elements of coal cleaning rejects.
abstract: The geochemical characteristics of coal cleaning rejects (CCR) in Santa Catarina State, Brazil, were investigated. Around 3.5 million ton/year of coal waste are dumped in Santa Catarina State. Coal beneficiation by froth flotation results in large amounts of CCR composed of coaly and mineral matter, the latter characterised by the occurrence of sulphide minerals and a broad array of leachable elements. The total and leachable contents of more than 60 elements were analysed. Atmospheric exposure promotes sulphide oxidation that releases substantial sulphate loads as well as Ca2+, K+, Mg2+, Cl- and Al3+. The metals with the most severe discharges were Zn, Cu, Mn, Co, Ni and Cd. Most trace pollutants in the CCR displayed a marked pH-dependent solubility, being immobile in near-neutral samples. The results highlight the complex interactions among mineral matter solubility, pH and the leaching of potentially hazardous elements.
authors.affiliation: Catarinense Institut of Environmental Research and Human Development-IPADHC, Capivari de Baixo, Santa Catarina, Brazil.
authors.forename: Luis F O
authors.initials: LF
authors.lastname: Silva
authors.forename: Maria
authors.initials: M
authors.lastname: Izquierdo
authors.forename: Xavier
authors.initials: X
authors.lastname: Querol
authors.forename: Robert B
authors.initials: RB
authors.lastname: Finkelman
authors.forename: Marcos L S
authors.initials: ML
authors.lastname: Oliveira
authors.forename: Marcus
authors.initials: M
authors.lastname: Wollenschlager
authors.forename: Mark
authors.initials: M
authors.lastname: Towler
authors.forename: Rafael
authors.initials: R
authors.lastname: Pérez-López
authors.forename: Felipe
authors.initials: F
authors.lastname: Macias
mesh_terms: D001938:Brazil; D003031:Coal; D004784:Environmental Monitoring / Q000379:methods*; D008906:Mining
chemical_list: D003031:Coal