Comparative Analysis of Potentially Toxic Elements (PTEs) in Waste Rock and Tailings: A Case Study from the Recsk Mining Area, Hungary

Metal-mining activities inevitably generate contaminants in high quantities, which can pose a risk to soil, water, biota, and humans. This study compares the geochemical properties of waste materials of tailings and waste rock heaps originating from the same high-sulfidation-type epithermal mineralization. Field sampling was conducted in the Recsk Copper Mining Area on the H2 tailings and H7 waste heap, where a total of 48 samples were collected at various depths. The results showed that PTEs were present in varying concentrations and behaved differently in the two waste materials. Copper concentrations were approximately five times higher in H2 tailings (median 1660 mg/kg) than in H7 waste rock (median 347 mg/kg), whereas arsenic was 2.8 times more concentrated in H2 tailings (674 mg/kg vs. 238 mg/kg). Conversely, zinc (114 mg/kg vs. 24 mg/kg), lead (172 mg/kg vs. 42.8 mg/kg), and cadmium (0.83 mg/kg vs. 0.097 mg/kg) show significantly higher concentrations in H7 waste rock. Element mobility analyses revealed that calcium mobility in H7 waste rock (65%) was twice that observed in H2 tailings (32%), with copper showing a threefold higher mobility in H7 despite lower total concentrations. NAG pH values (2.06–3.23) confirmed significant acid-generating potential in both waste types, with the H7 waste rock posing greater immediate environmental risk due to higher element mobility and more advanced weathering indicated by elevated jarosite (4.05%–8.01%) and secondary mineral contents. These findings demonstrate that, despite originating from the same mineralization, the distinct processing histories and physical properties of these materials necessitate unique approaches for successful remediation or secondary raw material extraction.