POTENTIOMETRIC MEASUREMENTS OF COPPER DIFFUSION IN POLYCRYSTALLINE CHALCOCITE, CHALCOPYRITE AND BORNITE

Diffusion measurements have been performed by an electrochemical poten tiometric method on polycrystalline synthetic chalcocite (Cu2S), chalc opyrite (CuFeS2) and bornite (Cu5FeS4) in the temperature range 5-50 d egrees C. The chemical ((D) over tilde) diffusion coefficients (in cm( 2)/s) are as follows: chalcocite, (D) over tilde = 38.7 exp(-5600/T); chalcopyrite, (D) over tilde = 15.4 exp(-6000/T) and bornite, (D) over tilde = 14.5 exp(-4900/T). The component diffusion coefficients (D) a re obtained by using the thermodynamic factor, this being 4250, 6500 a nd 1500, respectively. The diffusion coefficients obtained are in reas onable agreement with literature data, even for chalcopyrite and borni te, with Values previously acquired with a tracer technique at much hi gher temperatures.