Interactions between Chalcopyrite and Marmatite during Bioleaching Process

Chalcopyrite (CuFeS2) and marmatite [(Zn, Fe) S] are associated together most of the time in the raw ores and flotation concentrates. In this work, the interactions between chalcopyrite and marmatite during bioleaching by moderately thermophilic bacteria were investigated by electrochemical measurements and bioleaching experiments. In the initial stage of bioleaching of mixture of chalcopyrite and marmatite, the dissolution of marmatite was preferential, and was significantly accelerated with the addition of chalcopyrite because of the galvanic effect and catalytic effect of Cu2+ ions, while the dissolution of chalcopyrite was inhibited mainly due to the galvanic effect before the accomplishment of marmatite dissolution. Chalcopyrite dissolves fast when the dissolution of marmatite is finished, and small amount of marmatite cannot inhibit the final copper extraction of chalcopyrite if leaching time was long enough. Therefore, stepwise or selective bioleaching was feasible in processing mixture of chalcopyrite and marmatite to avoid complex flotation process in separating chalcopyrite and marmatite.