Fractionation of metal(loid)s in three European mine wastes by sequential extraction

Mine waste can constitute environmental hazards, especially when poorly managed. Environmental assessment is essential for estimating potential threats and optimizing mine waste management. This study evaluated a potential environmental risk of sulfidic mine waste samples originating from the Neves Corvo Mine, Portugal and the closed Freiberg mining district, Germany. Metal(loid)s in the waste samples were partitioned into seven operationally defined fractions using the Zeien and Brummer sequential extraction scheme. Results showed similar partitioning patterns for the elements in the waste rock and tailing samples from Neves Corvo Mine; most metal(loid)s showed lower mobility as they were mainly residual-bound. On the contrary, the Freiberg tailing had considerably elevated (24-37%) mobile fractions of Zn, Co, Cd and Mn. The majority of Fe (83-96%) in all samples was retained in the residual fractions, while Ca was highly mobile. Overall, Pb was the most mobile toxic element in the three samples. A large portion of Pb (32-57%) was predominantly found in the most mobilizable fractions of the studied waste samples. This study revealed that the three mine wastes have a contamination potential for Pb, which can be easily released into the environment from these wastes.