Experimental study of efflorescence salt crusts formation in tailings dams: Possibility of metal recovery
Roberto Rodríguez, Ángel Brime, Gabriel Gascó, Carlos Pérez-Jodra, Ana Martín-Martínez, Cristóbal García-García, Ana Méndez
Abstract
The objectives of this research are: (1) to study the process of formation of efflorescence salt crusts (ESC) on the surface of tailings dams, (2) to evaluate the possibility of recovering critical metals and raw materials, and (3) to study its effectiveness as a tailings (MT) decontaminant. To achieve these objectives, the evaporation process of 3 columns containing a mixture of MT and distilled water was monitored under laboratory conditions. Two MT of the flotation process from the extraction of Pb-Zn were used, one from the Mazarrón mining district (MDM) and the other from the Cartagena-La Unión mining district (CLUDM). MT and ESC were analysed by particle size analysis, mineralogical and chemical composition, thermal analysis, pH, electrical conductivity, potential redox, gravimetric water content and suction. It is important to note that some critical metals according to the EU 2020 CRWs, list are present in the MT sample. A significant growth in Zn ESC concentration was observed during the experiment. The concentration in MDM ESC is 8% higher than in the MT and in the CLUDM ESC it is 10% higher than in the MT. These results, together with the fact that ESC is water soluble, indicate the great potential of ESC treatment for metal recovery and MT decontamination.