Unlocking Critical Raw Materials from Copper Waste Dumps at Roșia Poieni: Implications for Sustainable Resource Recovery

This is the authors' abstract. We don't add key points for this paper.

Valorising mining waste is critical for sustainable resource management and reduced reliance on primary raw materials. Waste dumps from large-scale porphyry systems are potential secondary sources of critical raw materials (CRMs) as listed in Regulation (EU) 2024/1252. This study investigates mineralogical and microchemical heterogeneity in wastes from the Roșia Poieni porphyry copper district, Romania, testing the hypothesis that this heterogeneity governs both their secondary-resource potential and their environmental behaviour. Samples from the Geamăna and Halda Veche waste dumps were characterised by powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Raman spectroscopy. PXRD of five selected samples revealed marked inter-sample variability: chalcopyrite ranged from 12.88% to 13.48%, bornite and rutile reached 7.84% and 7.60%, and cuprite reached 15.78%. SEM-EDS confirmed Cu-rich bornite (55.25 wt.% Cu), while Raman spectroscopy identified melanterite alongside calcite and dolomite. The identification of pyrite, melanterite, and carbonate minerals suggests potential acid-generating and acid-neutralising processes, although validation by leaching tests and acid-base accounting is required. These findings establish a mineralogical basis for evaluating targeted recovery of critical and strategic raw materials alongside environmentally responsible mine waste management within a circular-resource framework; representative bulk geochemical analyses and recovery tests are still required to establish recoverable resources.