Inventory of the mining wastes located at the Iberian Pyrite Belt (IPB)

The Iberian Pyrite Belt (IPB), located in the SW of Iberian Peninsula, hosts the largest massive sulfide deposit globally, and over two centuries of intensive mining activity have generated huge amounts of abandoned mining waste along this region. Due to the limited information on the volume of the mining tailings, the main objective of this study has been to develop a volumetric inventory of these wastes by using Unmanned Aerial Vehicles (UAVs). For this purpose, Digital Elevation Models (DEM) and Triangular Irregular Networks (TIN) were developed, finding that the estimated waste reserves were 23.3 Mt (1.77∙107 m3) for the selected mining areas. The concentrations of both major and trace elements, and natural radionuclides were determined. Total reserves of Fe (2.12 Mt in Almagrera, Sotiel Coronada), and other metals/metalloids were calculated; highlighting 0.05 Mt for Zn in Riotinto, 0.06 Mt for Pb in Sotiel Coronada and 989 t for Rare Earth Elements in total. Nevertheless, natural radionuclide levels are similar to those found for unperturbed soils (25 Bq kg−1 of 238U, 21 Bq kg−1 of 232Th, and 224 Bq kg−1 for 40K). As potential applications for these mining stockpiles, techniques of Fe, Zn, Pb and REE recovery and uses as building materials are proposed for their valorization and to promote the circular economy.