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

• Developed the first volumetric inventory of mining stockpiles across 12 mines of the Iberian Pyrite Belt using UAV-based photogrammetry. • Estimated total reserves of 23.3 Mt and 1.77∙10 7 m 3 of abandoned mining wastes. • Identified high concentrations of Fe (up to 1.84 Mt in a single mound), Pb, Zn, and Rare Earth Elements. • Demonstrated that natural radionuclide levels are comparable to uncontaminated soils, minimizing radiological risks. • Proposed valorization strategies (Fe recovery for pigments/cement, Pb–Zn geopolymerization, REE leaching) to foster circular economy approaches. 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∙10 7 m 3 ) 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 238 U, 21 Bq kg −1 of 232 Th, and 224 Bq kg −1 for 40 K). 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.