Interactions between marmatite and bornite during the oxidative dissolution process in abiotic and biotic systems

Marmatite and bornite are commonly associated together in nature, and their interactions in an acidic
environment are vital for both (bio)hydrometallurgy and acid mine drainage (AMD) production. In this
work, dissolution experiments (marmatite : bornite ¼ 2 : 0, 3 : 1, 1 : 1, 1 : 3 and 0 : 2) accompanied by
analytic techniques such as electrochemical methods, Raman spectroscopy and synchrotron radiation-
XRD (SR-XRD) were utilized to interpret the interactions between marmatite and bornite in acidic abiotic
and biotic systems. The dissolution experiments showed that marmatite can significantly accelerate the
oxidative dissolution of bornite, especially in the abiotic system. On the contrary, bornite inhibited the
oxidative dissolution of marmatite when the percentage of bornite was high. Electrochemical
measurements proved that the galvanic interactions between marmatite and bornite were slight and
should not be the main cause for the interactions. Combined with the dissolution experiments, analytic
techniques and previous references, it could be speculated that marmatite accelerated bornite
dissolution mainly by providing an iron source, which acted as the energy source for microorganisms
and oxidants. Bornite affected the dissolution of marmatite mainly by Cu2+ ions dissolving from bornite.
Bornite inhibited the oxidative dissolution of marmatite mainly because a high Cu2+ concentration could
significantly hinder marmatite dissolution. In addition, the formation of elemental sulfur or jarosite was
also one important cause. Bornite intensified marmatite dissolution when the percentage of bornite or
the Cu2+ concentration was extremely low and then, a synergic dissolution process occurred.