Balancing between environmental pollution and unutilized resource potential: mine wastes of North Macedonia

Although North Macedonia covers only 0.7 % of the Earth's surface, it contains 3 % of the world's mineral deposits (Jovanovski et al. 2018). Both historical and recent mining operations in the country have left extensive waste deposits, particularly from operations focused on the exploration of antimony (Sb), arsenic (As), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn) and thallium (Tl). Over the past six years, we have intensively studied the mineralogy and geochemistry of two abandoned deposits, Lojane, a former Sb-As-Cr mine, and Allchar, a former Tl-As-Sb-Au mine (Đorđević et al. 2019, 2021; Kolitsch et al. 2018; Serafimovski et al. 2023; Vaňek et al. 2024). Historical mining practices, characterised by inadequate waste management, have resulted in huge accumulations of mining and processing wastes containing both economically valuable (Sb, As, Ba, Ni, Co, Pb, Cu, Zn) and environmentally hazardous elements (Cd, Cr, Hg, Tl). These sites now present a double challenge: environmental pollution and untapped resource potential.

The prediction of the environmental impact or strategic potential of these wastes is based on their mineralogical composition. Therefore, the precise characterisation of the host minerals and the possibility of their sequestration by secondary minerals is crucial for understanding such potential. At both the Lojane and Allchar deposits, we investigated the retention of As, Ba, Cr, Ni, Sb and Tl within secondary minerals in different mine waste environments. Minerals like scorodite, roméite-group antimonates, and pharmacosiderite-group minerals have been identified as significant reservoirs for arsenic (As), antimony (Sb), and thallium (Tl). These minerals help immobilize these elements, reducing their immediate environmental mobility. The high concentrations of valuable elements (e.g., Sb, Tl, and Ni) in both primary and secondary minerals from the various waste environments (waste rock, tailings, technosols) present opportunities for resource recovery. Effective leaching and extraction technologies could turn these environmental burdens into economic assets.

By identifying specific mineral reservoirs and understanding their mobilisation potential, our research contributes to the development of contamination risk management strategies for polluted sites, linking mineralogical processes to practical environmental remediation requirements. Furthermore, by turning these environmental burdens into assets, Northern Macedonia has the potential to set a regional example for the long-term management of mine waste.