Mineralogical phase transformation of Fe containing sphalerite at acidic environments in the presence of Cu2+

Dissolution of the exposed sphalerite (marmatite) in abandoned mining sites and tailings may exacerbate acid and metalliferous drainage (AMD) hazards. Cupric ions are inevitable ions in AMD systems but its action mechanism on the dissolution of sphalerite is still unclear. In this work, the possible phase transition from sphalerite to chalcopyrite is firstly discovered in acidic cupric ions solution according to the results of Raman and (synchrotron radiation-based) X-ray (micro-) diffractometer spectra, which should be an important reason that mediates the dissolution of sphalerite. Results of DFT calculations reveal the underlying mechanism that Cu2+ can selectively replace zinc in marmatite lattices and further diffuse into the matrix. Additionally, a strong correlation between the cupric ion consumption with the pH value variation is discussed and the effects of the formed new phase on the dissolution kinetics of marmatite were researched. According to this work, the action mechanism of cupric ions on sphalerite dissolution in acidic environments is furtherly clarified.

Automated summary

The study found a possible phase transition from sphalerite to chalcopyrite in acidic cupric ions solution, where the cupric ions can selectively replace zinc in marmatite lattices and diffuse into the matrix, forming a strong correlation with pH value variations. This clarifies the action mechanism of cupric ions on sphalerite dissolution in acidic environments.