The passivation of chalcopyrite subjected to ferric sulfate leaching and its reactivation with metal sulfides

Research has been undertaken on the passivation of chalcopyrite when subjected to leaching in ferric sulfate medium. The sulfur film which forms on chalcopyrite in the oxidation process is not responsible for the decrease in the rate of copper dissolution observed. The passivating effect created by a reaction product other than sulfur is neutralized to some extent by introduction into the crystal lattice of the passivated solid, metal sulfides such as HgS, As₂S₃, SnS and CoS, so that the metal sulfide nuclei deposited on the passivating layer restore the initial reactivity between the solid and the leaching solution.