“…However, they are weathered in contact with water and oxygen, releasing metal ions and sulphuric acid (Younger et al, 2002). As a result of the weathering process, the AMW contains elements dissolved in high concentrations, such as heavy metals (e.g., Cu, Zn, Fe, Cd), non-metals (e.g., As, Se) and sulphuric acid (pH = 1-3), as well as rare earth elements (REE) at low concentrations (Ayora et al, 2016;Bwapwa, 2017;López et al, 2019a). For that reason, AMWs are considered a source of valuable metals and a source of process water (García et al, 2014).…”