Passivation of chalcopyrite during oxidative leaching in sulfate media

Abstract Sulfate-based leaching processes for chalcopyrite (CuFeS 2 ) are attractive because of their inherent simplicity. Unfortunately, high copper extractions are not attainable in a reasonable residence time unless the leaching temperature exceeds 200°C (oxygen pressure leaching) or chalcopyrite is ‘activated’ by a pretreatment method prior to leaching. In the present work, the oxygen pressure leaching behaviour of chalcopyrite in the temperature range 110–220°C was studied to shed new light on the reasons for the slow leaching. Mineral surfaces were examined by Auger electron spectroscopy and X-ray photoelectron spectroscopy to identify the presence of any passivating layers that may form during leaching. The results suggest that chalcopyrite is passivated by a thin ( n where n > 2. The leaching kinetics at low temperature (110°C) can be explained in terms of a mixed diffusion/ chemical reaction model where the reaction rate is ultimately controlled by the rate at which the copper polysulfide leaches.

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