Abstract: The effects of silver on the chalcopyrite leaching have been studied. No catalytic effect was found when FeCl₃ and CuCl₂ were used as oxidizing agent. In the case of Fe₂(SO₄)₃ and MnO₂ the reaction rate constants were found to be increased 200 times as compared with that without silver additives. In the acidic Fe₂(SO₃)₂ leaching of chalcopyrite the reaction rate is controlled by ion diffussion through the elemental sulfur layer. The apparent activation energy is 35.7 kJ/mol. The order of reaction is 1.5 with respect to silver ion concentration and first order with respect to ferric ion concentration. The rate Constant of the diffusion controlled reaction is inversely propotional to the square root of the initial radius of chalcopyrite particles. The overall reaction kinetics equation has been derived.

Key words: chalcopyrite, ferricsulfate, silver ion, catalytic leaching