Electrochemical Mechanism of Copper Activating Sphalerite

Flotation recovery of sphalerite as a function of pH with butyl xanthate as a collector in the presence and absence of activator is presented in Fig. 6.1. Evidently, sphalerite exhibits good flotation in weak acidic media and the recovery decreases sharply with the increase of pH in the absence of activator. The flotation of sphalerite is activated in wide pH range in the presence of activators such as CUSO4 or Pb(N03)2. The recovery of sphalerite can be above 90% at pH 12 using copper ion as an activator and at pH 10 using lead ion as an activator. 

The electrochemical mechanism of cupric sulphate activating sphalerite has been studied. The measured cyclic voltammogram curves in aqueous solution at different pH with sphalerite compound electrode are shown as solid lines in Fig. 6.1. 

At pH= 6.0, the anode peak appearing in the first potential scan corresponds to the reaction  

It may be derived that elemental sulphur is not the final product of surface oxidation of sphalerite, because the potential associated with the second anode peak corresponds to the thermodynamic potential of the reaction (3-1 la) (taking potential barrier of SO into consideration). 

The first cathode peak appearing in inverse scan is corresponding to the reaction in which SO is reduced to element S again. The second cathode peak with a lower potential contains two reactions. 

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