Physical and Chemical Characterization of an Abandoned Layered Pb-Zn Mine Tailing

Abstract

A physical and chemical characterization of an abandoned Pb-Zn mine located in Gyongyosoroszi-Hungary was carried out in tailing samples assuming a saturated state owing to precipitation. Results showed that mine waste behave physically as a well graded permeable sand. Besides, precipitation can produce and effective vertical stress of 0.89 kPa compared to unsaturated conditions. A rapid rise in water table of 2.21 m over the ground surface is neccesary to produce liquefaction. Chemical characterization carried out by SEM and XRF analyisis showed that iron (Fe) and sulfur (S) were the dominat elements. Thereby, pyrite (FeS2) was preliminary suspected and confirmed with the oxidation kinetics. Indeed, oxidation of the pyrite in the tailings is a rapid reaction in the first orden of magnitude with a reduction of pH along with SO42- and Fe3+ production. Finally, geochemical modelling at equilibrium was applied by using MINTEQ. Saturation index (SI) showed that Fe3+ precipitates as goethite, hematite and lepidocrocite. Conversely, hydroniumjarosite dissolution is produced.