Multitechnique Characterization and Comparative Analysis of the Geochemical Dynamics of Polymetallic Mine Tailings from Central Peru Using XRD, SEM-EDS, ICP-OES, and k₀-INAA

Abstract

Mine tailings are heterogeneous materials whose mineralogical and elemental compositions reflect the nature of the original ore deposit, beneficiation processes, and post-depositional physicochemical transformations. In this study, six tailings samples from different mining deposits in central Peru were characterized: RA-00 (Alpamina, Junín), 3MCP (Quiulacocha, Pasco), RQ-00 (Peña Blanca, Junín), GE05 (Millotingo, Lima), M8 (Atacocha, Pasco), and M9 (El Porvenir, Pasco). The objective was to establish their mineralogical and elemental associations and compare their geochemical behavior in relation to valorization potential and environmental significance. The methodology integrated X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), inductively coupled plasma optical emission spectrometry (ICP-OES), and instrumental neutron activation analysis using the k₀-standardization method (k₀-INAA). The results revealed distinct mineralogical and geochemical behaviors. M8 and M9 are predominantly carbonate-rich, dominated by calcite and quartz with residual pyrite, whereas 3MCP is strongly sulfide-rich, containing 69.8 wt.% pyrite. RA-00 and RQ-00 show greater alteration, characterized by jarosite and muscovite, while GE05 displays transitional behavior with ferromagnesian carbonates and secondary hydrated sulfates. These mineral associations are relevant for interpreting elemental reactivity and mobility. k₀-INAA revealed marked multielemental variability. In 3MCP, 171.47 mg/kg Ag, 1543.12 mg/kg Cu, 526.83 mg/kg Mo, and 1492.47 mg/kg As were determined, indicating both valorization potential and environmental relevance. RQ-00 showed the highest concentrations among the rare earth elements evaluated. Overall, the integrated approach established relationships among composition, mineralogy, and degree of alteration, providing criteria for selecting materials with metal recovery potential and guiding monitoring and remediation strategies under a circular economy approach.

Keywords: polymetallic mine tailings; geochemical dynamics; k₀-INAA