Characterization of mining tailings in México for the possible recovery of strategic elements

The supply of minerals and energy is critical to a global society. Extraction of minerals results in the concurrent production of a significant volume of waste material, including tailings. The volume of tailings is normally far more than the liberated resource, tailings may be reprocessing because they often contain significant amounts of potentially valuable elements. The physicochemical, mineralogical and elemental characterization of nine different samples of mining residues from the exploitation of both iron ores and polymetallic minerals (Pb-Zn-Ag) was done to evaluate the possibility of recovery of strategic elements, like Ga, In, Ge and/or rare earth elements. The mineralogical characterization was carried out by X-ray Diffraction and Scanning Electron Microscopy with Energy Dispersive X-ray analysis. The elemental characterization was performed by total digestion and Inductively Coupled Plasma Atomic Emission Spectrometry with a Mass Spectrometer detector and Instrumental Neutron Activation Analysis. The results indicated that the major elements (>100 mg/kg) in the samples are Fe, Zn, Pb and Cu. The strategic elements with the greatest recovery potential are Ga, Y, La, Ce, Nd and Sc from iron non-oxidized tailings, indium from a Zn refinery hydrometallurgical waste. While in the old oxidized Pb-Zn-Ag tailings the recovery of Au in particle less than 250 μm is viable.