Mineralogical control and economic barriers for tailings reprocessing

The continuous development of modern technologies and their constant growth in demand have resulted in a surge in the demand for raw materials since the 20th century. However, a significant portion of the supply still originates from primary sources, which result in significant environmental and social impacts. A substantial part of these environmental problems arise from the production of mine tailings. Simultaneously, the continuous increase in production, development of processing technologies, and increased prices often result in a higher amount of tailings produced per output of target material, due to higher volume extracted jointly with a reduction of the cutoff grade.The EU's Critical Raw Materials Act (CRMA) highlights the strategic importance of 34 critical and 17 strategic raw materials (SRMs), with the latter including copper. To mitigate the environmental and supply risks associated with primary extraction, the development of secondary sources is emphasized. Mine tailings represent a significant potential resource, yet systematic frameworks for their valorization require development. This study addresses this gap through a systematic review of 66 articles on copper processing. By synthesizing this data, it seeks to elucidate how deposit geology and beneficiation processes control tailings composition and, in turn, dictate viable pathways for copper recovery.

This study considers that site dependency stems from predictable geological factors. Accordingly, the original mineralogy is defined by the deposit’s genesis and preservation conditions. This assemblage is then overprinted by the extraction process, which modifies its physical state (e.g., liberation, grind) and changes its surface and bulk chemistry through reagent residues, pH modifiers, and induced oxidation. Finally, long-term storage conditions drive the material’s geochemical evolution through oxidation and secondary mineral formation. The culmination of this pathway is a tailings mineralogical signature that pre-selects feasible recovery processes. The goal of our global data collection is to test this hypothesis by mapping these mineralogical signatures against reported processing outcomes, thereby building a predictive framework for route selection for copper reprocessing from mine tailings.

The analysis defends an integrated, site-adjusted framework where the predictive power of deposit geology and tailings mineralogy guides initial process screening but must be tested against four viability criteria: the ability to generate a marketable concentrate, adaptation to local constraints (climate, water, infrastructure), sufficiency of data for design, and a recalibrated economic model that incorporates pollution abatement costs as value drivers, not externalities. To overcome data gaps and extreme site-specificity, success depends on building a global library of mineralogical analogues using advanced characterization (e.g., automated mineralogy, hyperspectral sensing), enabling the extrapolation of proven flowsheets to new sites. This synergetic approach, valuing environmental and social risk reduction alongside metal valorization, is essential to transform tailings from a liability into a strategically viable, circular resource, reducing the pressure on raw material supply chains.