An Electrochemical Study of Surface Oxidation and Collectorless Flotation of Pyrite

摘要

Pyrite is a common sulfide mineral and its surface oxidation and natural hydrophobicity play animportant role in determining flotation performance for many minerals, particularly for sulfides andcoal. In this study freshly fractured electrodes have been used to investigate the surface oxidation offresh pyrite surface and collectorless microflotation tests were performed to study its naturalhydrophobicity. Chronoamperometry performed on in-situ fractured electrodes demonstrated thatpyrite oxidation takes place at potentials of -0.28 V (SHE) at pH 9.2 and 0 V at pH 4.6, considerablylower than previously assumed. Incipient oxidation at slightly more positive potentials produce ahydrophobic sulfur-rich species, most likely a polysulfide or metal-deficient sulfide, which impartsnatural surface hydrophobicity to pyrite. Collectorless microflotation test results have indicated thatpyrite acquires considerable floatability upon superficial oxidation. The collectorless flotationrecovery of pyrite is determined by the relative amounts of polysulfide, soluble species, and insolublespecies produced during oxidation, which depends on solution pH and potential.