Search

Mineralogical controls on waste-rock weathering rates are important for mine water quality predictions, as the reactivity of minerals is impacted not only by its chemical composition, but also by its texture, arrangement, and association. In this study, seven-year on-site field barrel kinetic tests were conducted with different types of waste rock from the Antamina mine, Peru. Quantitative automated mineralogy was applied to characterize mineral texture, liberation, and association during weathering and used to examine mobilization and attenuation mechanisms. The weathering of reactive intrusive waste rock with low neutralization potential led to mobilization of Cu, Fe, and Zn, and was associated with >75% liberated Fe-, Cu-, or Zn-bearing sulfide minerals and galvanic coupling of pyrite with chalcopyrite and sphalerite. In contrast, the mobilization of Cu, Fe, and Zn was less effective in skarn waste rock types with high neutralization potential, where <70% Cu-, Fe-, and Zn-bearing sulfide minerals were liberated and passivation of pyrite surfaces occurred. Finally, waste rock weathering and drainage quality trends were simulated using a reactive transport model, and calibration of sulfide dissolution rates quantitatively affirmed the observed changes in mineralogical waste rock associations and liberation. This study thus demonstrates that accounting for mineralogical parameters using automated mineralogy may improve practical predictive models for mine waste water management. Image 1 • Integrated mineralogical and geochemical analyzes from a long-term kinetic field barrel monitoring program. • Characterization of waste rock reactivity using quantitative automated mineralogy and drainage quality data. • Reactive transport modeling of geochemical and mineralogical controls on long-term drainage composition. • Drainage chemistry is affected by waste rock mineral arrangements in addition to bulk geochemical composition. [ABSTRACT FROM AUTHOR]