Geochemical, mineralogical, and microbiological studies in the Pan de Azúcar abandoned mine (Northwest Argentina): keys for future remediation option selection

MURRAY JESICA; KIRSCHBAUM ALICIA; DOLD BERNHARD

Viña del Mar

Congreso; MineClosure2010; 2010

Gecamin, Chile

The Pan de Azúcar abandoned mine is located at the Norhwest region of Argentina, at 3300 m.a.s.l. It is also situated near one of the most important affluent in the Pozuelos basin, a Natural Reserve. The climate is arid, with 200 mm of precipitation per year. Extreme temperature variation, scarce vegetation, and eolic transport are characteristic. Pb-Zn-Ag were the metals recovered after the benefaction process which included milling and flotation. The underground mine was exploited through galleries and piques until level -210m. The small operation ceased in the 1990. To approach the anthropogenic and natural system processes and evaluate possible remediation scenarios, the here presented investigation will include: -Mineralogical and geochemical characterization of the tailings and rock waste dumps (microscope, XRD, sequential extractions). -Superficial and underground water characterization (heavy metals concentration, stable isotope). -Microbiological identification and influence (DNA, Fluorescent “in situ” Hybridization (FISH)) Evaluation of economic concentrations of Pb, Ag, Zn in tailings and waste rock dumps in order to evaluate possible retreatment. Remediation options will then be evaluated as best practice. It could be mencioned: Evaluation of the formation of hardpan and cementation zone as a natural protection layers which might limit the oxidation process, measures in order to avoid the erosion and further water infiltration, flooding and vegetation are not seen as suitable option due to the arid climate conditions.