Effect of activated carbon on chalcopyrite bioleaching with extreme thermophile Acidianus manzaensis

The effect of activated carbon on chalcopyrite bioleaching by extreme thermophile Acidianus manzaensis YN25 at 65 °C was evaluated, together with the investigation of the sulfur speciation transformation on the mineral by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy. Bioleaching experiments show activated carbon significantly accelerated the dissolution of copper from chalcopyrite concentrate. The optimum concentration of activated carbon enhancing copper dissolution is 2 g/L, under which the copper yields increased from 64% to 95%. The catalysis could mainly be attributed to the galvanic interaction between activated carbon and chalcopyrite. Jarosite, elemental sulfur and chalcocite were detected in the solid phase, and the formation of potassium jarosite was prior to ammonio-jarosite. Activated carbon did not change the species of sulfur-containing compounds, but accelerated the formation of them.

Research Highlights
► Activated carbon can lead to increase in copper extraction yield in chalcopyrite bioleaching by extreme thermophile A. manzaensis YN-25, e.g., with the optimum activated carbon concentration of 2 g/L, the copper yields can be increased from 64% to 95% within 10 days.
► Sulfur speciation analyses evidenced the formation of chalcocite when the Eh is below a critical potential.
► Activated carbon did not change the species of sulfur-containing compounds, but accelerated the formation of them.