Separation of Chalcopyrite and Galena by Xanthate Flotation using Starch Xanthate as a Depressant for Galena

The effect of starch xanthate on the separation of chalcopyrite and galena was studied in the flotation using potassium ethyl xanthate (KEX) as a collector. Starch xanthate synthesized was found to contain a xanthate radical at the rate of one part per 82 glucose units of starch.Galena was depressed preferentially by starch xanthate and recovered as a sink. The best result obtained in the flotation carried out on an artificial mixture (1:1 by weight) revealed as follows: chalcopyrite as a float, recovery=97% and grade=83%; galena as a sink, recovery=83% and grade=97%, respectively.KEX was adsorbed on galena forming a multilayer lead xanthate by metathesis reaction with oxidized products on galena surfaces, while KEX was adsorbed on chalcopyrite surfaces as a monolayer that ensures the hydrophobicity of chalcopyrite.Starch xanthate produced a hydrophilic multilayer film on galena surfaces whereby galena is depressed effectively. Muchl ess adsorption of starch xanthate was obtained on chalcopyrite surfaces than that on galena surfaces. This provides major reason for selective depression of galena.Starch was also adsorbed on both chalcopyrite and galena surfaces with almost the same adsorption density which is much less than that of starch xanthate. No successful separation of chalcopyrite and galena was achieved with starch.