ELECTROCHEMICAL INTERACTIONS BETWEEN SULFIDE MINERALS AND GRINDING MEDIA AND THEIR EFFECTS ON FLOTATION AND MEDIA WEAR

The electrochemical nature of mineral-grinding media interactions in the wet grinding of one- and-two-sulfide-mineral ores was investigated with regard to the corrosive wear of the media and the flotation behavior of the minerals. Two iron sulfides (pyrite and pyrrhotite) and three types of steels (mild steel, high carbon forged steel and austenitic stainless steel) were used to represent the sulfide minerals and the grinding media, respectively. Electrochemical measurements (rest and combination potentials, galvanic currents, polarization behaviors) under abrasive and non-abrasive conditions were correlated with data from marked ball wear tests; Halimond tube flotation tests and with scanning electron photomicrographs and energy dispersive X-ray specta.;Corrosion currents obtained by superposition of polarization curves of sulfide mineral/grinding media systems were in good agreement with corrosion currents estimated from ball wear data. It was also found that freshly abraded metallic debris particles generated by abrasive wear of the grinding media lowered the corrosive wear of the media by affecting the electrochemical behavior of the minerals. This effect was particularly strong on a magnetic mineral such as pyrrhotite. The adverse effect of mineral-grinding media interactions on the floatabilities of pyrite and of pyrrhotite in the single-mineral systems was partially reversed in a two-mineral/grinding media combination. A parallelism was found between these floatability changes and the galvanic behaviors of the minerals in the two- and three-electrode systems.