Current Developments in the Hydrometallurgical Treatment of ...

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Current Developments in the HydrometallurgicalTreatment of Copper Ores and ConcentratesGALVANOX CHEMISTRY‣ Typically, chalcopyrite surfaces are passivated (i.e., theybecome resistant to electrochemical breakdown) in ferric sulfatesolutions at even modest solution potential levels.‣ It is widely held that this results from the formation of some sortof passivating film on the mineral surface that most likelyconsists of an altered, partially Fe-depleted sulfide layer.‣ Because of this, most investigators have assumed that it is theanodic half-cell reaction that limits the overall rate of leaching.‣ However, we discovered that it is primarily the cathodic half-cellreaction (i.e., ferric reduction) that is slow on the chalcopyritesurface.
Current Developments in the HydrometallurgicalTreatment of Copper Ores and ConcentratesGALVANOX CHEMISTRY‣ The presence of pyrite facilitates chalcopyrite leaching byproviding an alternative catalytic surface for ferric reduction inelectrical contact with the chalcopyrite‣ This essentially eliminates cathodic passivation of chalcopyrite inferric sulfate solutions.‣ Also, by ensuring that chalcopyrite oxidation is rapid relative toferrous oxidation, the solution potential is maintained at a levellow enough to prevent anodic passivation of the chalcopyrite‣ This also prevents anodic breakdown of the pyrite, whichremains more or less completely inert.
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Current Developments in the Hydrometallurgical Treatment of ...

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