From environmental burden to resource potential: environmental impact evaluation and Critical Raw Materials recovery from abandoned gold mining waste in the Western Alps (NW Italy)

Abstract Extractive waste (EW) from former mining activities poses long-term environmental impacts while representing a potential secondary resource. Within a circular economy framework, EW can be valorised to recover raw materials (RMs) and critical raw materials (CRMs) contributing to the supply of strategic resources. In the Anzasca Valley (Piedmont, Italy), gold mines of Crocette and Pestarena operated until the mid-20th century, producing large amount of EW. These materials have caused persistent contamination of soils and waters, particularly with As and other potentially toxic elements (PTEs). The aims of the study are i) to assess environmental contamination and ecological risk, and ii) to evaluate the potential for recovering CRMs from EW. To do so, the study combines mineralogical and geochemical data of soils and EW from different sampling campaigns. Results revealed significant enrichment of CRMs, particularly As, followed by W, Sb, Bi, and minor enrichment of some light REEs (La, Ce, Pr, Nd). The environmental impact assessment identified As as the main pollutant, classifying soils as heavily to extremely contaminated, with additional moderate contamination by Pb and Co, and indicating an overall moderate ecological risk. The estimated volumes of EW and residual amounts of selected CRMs (A, Bi, Sb, W) indicate a potential for concurrent recovery, with As as the primary target. The findings suggest that this approach can represent a sustainable intervention within remediation projects, combining environmental risk mitigation with the recovery of valuable resources and supply security.