The interaction of grinding media and collector in pyrite flotation at alkaline pH

A significant proportion of invisible gold is hosted by pyrite and the successful recovery of this gold requires a high recovery of pyrite in flotation. In the industry, the flotation of gold-bearing pyrite is operated in a broad range of pH and collector concentration with different types of grinding media. Following the previous study at pH 5.0 and 7.0, the current study investigated the interaction of grinding media with collector and its effect on pyrite flotation at pH 8.5. It was interesting to find that at the same xanthate dosage the highest pyrite flotation was achieved when forged steel, instead of 30% chrome steel, was used as the grinding media although it produced the highest quantity of iron contamination. Pulp chemistry measurement, surface analysis and electrochemical study revealed that pyrite oxidation prevailed over xanthate oxidation at pH 8.5 and pulp potential played a dominant role in pyrite flotation. At this pH, the high pulp potential generated by high chrome steel grinding media facilitated pyrite oxidation instead of xanthate oxidation, but the low pulp potential generated by forged steel grinding media still allowed xanthate oxidation, thus promoting pyrite flotation.