The above electrochemical measurements indicate that both the inhibition of surface reactions (surface cleaning effect) and the detachment of surface xanthate species contribute to the depressive effect on pyrite flotation. Free cyanide and cuprous cyanide play a similar role in terms of inhibiting xanthate oxidation and adsorption, while the surface cleaning effect of cuprous cyanide is relatively weaker than free cyanide. However, cuprous cyanide species depress pyrite flotation at a similar efficiency as free cyanide.