The stepwise dissolution of chalcopyrite bioleached by Leptospirillum ferriphilum

Chalcopyrite dissolution was evaluated by bioleaching and electrochemical experiments with Leptospirillum ferriphilum. The bioleaching of chalcopyrite was stepwise: it was reduced to chalcocite at a lower redox potential locating at initial 8 days of bioleaching process, but no reduced product was detected at a high level of redox potential about 550 mV (vs. SCE). Compared to the latter stage, the bioleaching rate was fast in the initial 8 days of bioleaching when the redox potential was low. The reduction reaction was beneficial to the dissolution of chalcopyrite. The formation of jarosite occurred during the later stage of chalcopyrite bioleaching, but it was porous and loose. Therefore, it cannot be an effective component of a passivation layer to block continuous copper extraction.