The influence of the impurities on the flotation behaviors of synthetic ZnS

To investigate the effect of three typical impurities (iron, copper and cadmium) on the flotation behavior of sphalerite, we have synthesized impurity-doped ZnS using a coprecipitation method. In the absence of CuSO4, the flotation tests show that Cd and Cu impurities greatly improve the recovery of ZnS, while Fe impurities apparently decrease the floatability of ZnS. The spectral results show that both dixanthogen and the metal xanthate are observed on Cu- and Cd-doped ZnS surfaces, but only metal xanthate is observed on Fe-doped ZnS surface. Xanthate adsorption tests show that Cd and Cu impurities favor xanthate adsorption, while Fe impurities decrease the adsorption of xanthate.In the presence of CuSO4, Cd impurities not only greatly improve the recovery of ZnS but also enhance the adsorption of xanthate. Cu impurities can improve the flotation of ZnS but show little influence on xanthate adsorption. Fe impurities apparently decrease both ZnS flotation and xanthate adsorption.

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► Fe impurities do not favor the flotation of ZnS, while Cu and Cd impurities favor that for ZnS.
► It is found dixanthogen only on Cd- and Cu-doped ZnS surface but not on Fe-doped ZnS.
► Fe impurities are also not favorable for Cu activation, and some of the Cd impurities can be substituted by Cu2+.
► The Fermi level of impurity-doped ZnS determines whether xanthate could flow electrons to ZnS.