Article

Electrochemical behavior of pyrite in the absence and presence of DTPI at acidic and alkaline conditions

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Abstract

This study investigates the electrochemical behavior of pyrite in collectorless and DTPI (sodium disobuthyldithiophosphinate) induced conditions to identify the nature of interactions between pyrite and DTPI with respect to pulp pH and pulp potential (Eh). Electrochemical investigation from acidic to alkaline (pH = 4.67- 11.0) conditions were performed using cyclic voltammetry technique in cathodic to anodic potential range (-505 to +595 mV SHE). DRIFT spectroscopy were also done after polarization at varying potentials and pH, to identify pyrite surface and to express adsorption mode of DTPI. Pyrite surface was seen to display characteristic electrochemical behavior according to pulp pH. Hydrophobic nature of pyrite in acidic condition turned into hydrophillic form with increase in solution pH with regard to the changes in pulp potential. In DTPI induced condition, intensity of redox reactions, related to S 0 formation, decreased at acidic pH due to surface passivation with DTPI adsorption. No apparent differences occurred in the pyrite volttamograms after DTPI addition in other pHs. Adsorbance of DTPI on pyrite relied mainly on chemical means, irrespective of pulp potential. DRIFT studies revealed that DTPI adsorbed in dimer form on pyrite and acidic pulp favored its adsorption. DRIFT patterns also confirmed that interaction among pyrite and DTPI relied mainly on chemical means.

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