Quantitative Mineralogy in Characterization of Historical Tailings: A Case from the Abandoned Balya Pb-Zn Mine, Western Turkey

This study investigated the abandoned Balya Pb-Zn mine tailing in Turkey. We performed sieve analyses, X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), major and trace element analyses, and SEM-based quantitative mineralogical analyses on collected samples. A schematic oxidation model comprising at least three stages is proposed based on the mineral paragenesis, textural properties of minerals, and elemental deportments. Oxidation caused the development of vertical zones such as vadose (oxidation) and capillary zones with physical, mineralogical, and chemical differences. For example, the near-surface vadose zone of sulfide oxidation contained intensely oxidized pyrite (18 wt.%) and 16 wt.% secondary minerals (As-bearing plumbojarosite, jarosite and gypsum). In contrast, the capillary zone representing a depth of 20-60 cm contained unaltered 13 wt.% pyrites, primary sulfides (e.g., sphalerite, galena, and arsenopyrite), and 23 wt.% secondary Mn-Fe-Zn-bearing oxy-hydroxides. The distribution of secondary minerals also reflected the elemental mobility depending on pH. Precipitation of plumbojarosite under acidic conditions limited the mobility of Pb and As, thereby keeping them in the vadose zone. Mn, Fe, and Zn seeped deep, and their mobility was limited by forming oxy-hydroxides at moderately acidic to circumneutral pH conditions in the capillary zone. The precipitation of the secondary minerals changed the textural properties of primary sulfides such as pyrite and galena restricted their reactivity, and caused a change in the rate and degree of oxidation over time. This case study showed that mineralogical constituents, key factors in the characterization of mine tailings, may change due to the secondary minerals, as in historical tailings with a long exposure time. Therefore, it should be noted that assessments based on the existing mineralogical properties of unoxidized tailing samples may cause uncertainties in determining the long-term behavior of the tailings.

Automated summary

This study investigated the abandoned Balya Pb-Zn mine tailing in Turkey and analyzed the mineralogical, structural, and elemental migration characteristics of the tailings. The results showed that oxidation caused the formation of vertical zones with different physical, mineralogical, and chemical properties. The precipitation of secondary minerals changed the textural properties and oxidation rate of primary sulfides, affecting the long-term behavior of the tailings.