Comparison of bioleaching and dissolution process of p-type and n-type chalcopyrite

- Bioleaching of p-type and n-type chalcopyrite was studied.
- Dissolution process of p-type and n-type chalcopyrite in bioleaching was studied.
- Semiconducting properties caused the different bioleaching behaviors.

In this work, bioleaching and dissolution processes of chalcopyrite from three different regions were investigated and compared mainly by leaching experiments, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical analysis. Hall effect experiments showed that one (chalcopyrite A) belonged to p-type chalcopyrite whose carrier concentrations were high, while the other two (chalcopyrite B and C) were both n-type chalcopyrite whose carrier concentrations were low. A remarkably higher copper extraction of p-type chalcopyrite could be achieved during bioleaching by L. ferriphilum compared with n-type chalcopyrite. Redox potential in bioleaching of p-type chalcopyrite can be maintained at the appropriate range (about 380-480 mV vs. Ag/AgCl) for a longer period of time. Acid consumption in bioleaching of p-type chalcopyrite was significantly lower than that of n-type chalcopyrite. SEM analysis indicated that p-type chalcopyrite was more easily corroded by microorganism than n-type chalcopyrite. XPS analysis revealed that monosulfide (S2−), disulfide (S22−), polysulfide (Sn2−) and sulfate (SO42−) were the main intermediate species during bioleaching of both p-type and n-type chalcopyrite. Electrochemical analysis showed that the electrochemical dissolution processes of p-type and n-type chalcopyrite were similar, while the conductivity and oxidation-reduction rate of p-type chalcopyrite was significantly higher than those of n-type chalcopyrite, thus resulting in significant higher electrochemical dissolution kinetics and copper extraction. This work is potentially useful in explaining the inconsistences in chalcopyrite hydrometallurgy.

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