Influence of grinding media, pyrite mineralogy and water chemistry on the galvanic interaction between grinding media and pyrite

The purpose of this study was to investigate the role of grinding media type, water chemistry and pyrite mineralogy on the galvanic interaction between grinding media and pyrite during grinding of a gold ore. The galvanic current between pyrite and grinding media increased with the electrochemical activity of the grinding media, while it decreased as a function of increasing chromium content in the media. Furthermore, changing the pyrite-based electrode from pure pyrite to a gold-bearing pyrite electrode increased the galvanic current between the pyrite and the grinding media electrodes; therefore, the gold-bearing pyrite electrode is more active than the pure pyrite one. In addition, using process water instead of tap water increased the galvanic current density between pyrite and the high-chromium grinding media electrode (30% chromium). However, when the forged steel or the low-chromium grinding media electrodes were used, the galvanic current decreased compared to the tap water condition. In addition, the results obtained from SEM-EDX analysis showed that in both tap and process water conditions, oxide species were identified on the surface of the forged steel and low chromium electrodes. However, no oxygen was detected on the surface of the 30% chromium grinding media.