Fungal degradation of elemental carbon in Carbonaceous gold ore

•Elemental carbon is altered by Phanerochaete chrysosporium.•P. chrysosporium reduces the interference (preg-robbing) of elemental carbon during cyanide leaching of gold ore.•The reduction of preg-robbing capacity of elemental carbon is attributed to degradation and passivation by P. chrysosporium.

Phanerochaete chrysosporium was used to decompose elemental carbon in Carbonaceous gold ore and enhance cyanide recovery of gold. The degradation of elemental carbon amounted to 34% due to fungal treatment for 14 days. A positive correlation between the fungal degradation of elemental carbon and the activity of degradation enzymes was noted. Organic acids and nitrogenous bases, which are generated by the fungi, caused the degradation of elemental carbon indirectly. P. chrysosporium caused a surface exfoliation of elemental carbon in the form of layers and the destruction of the microcrystalline and pore structure. The amount of oxygen-containing groups and of aliphatic groups was increased. The amount of aromatic rings, the specific surface area, the pore volume and the condensation index of aromatic rings were decreased. Also the thermal properties of elemental carbon changed significantly, whereas the amount of the low-stability compounds was increased. P. chrysosporium can reduce the interference of elemental carbon with the cyanide recovery of gold. The amount of gold recovery increased from 44% to 62%. This improvement is ascribed to the combined effect of degradation and passivation of elemental carbon by P. chrysosporium.