Surface chemistry of oxidised pyrite during grinding: ToF-SIMS and XPS surface analysis

In the processing of minerals, the ore is ground to small particles to liberate the valuable minerals which are then separated from the ore waste material by froth flotation. The conditions of the grinding process have an impact on the surface chemistry of the minerals which is critical for the subsequent flotation process. This study aims to investigate the effect of different grinding conditions on the evolution of the surface chemistry of pyrite during the grinding process. The hydrophobicity of the ground pyrite is determined using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and the surface chemistry speciation is characterized by X-ray Photoelectron Spectroscopy (XPS). The results show that when grinding with forged steel media, the new surfaces produced on pyrite particles during grinding are oxidised or react rapidly in the mill, resulting in low surface hydrophobicity. In contrast, when grinding with high chrome steel media under nitrogen gas atmosphere, the reaction rate of fresh surfaces can be markedly reduced, hence, increasing the natural hydrophobicity of pyrite. This paper provides a comprehensive understanding of how surface chemistry of pre-oxidised pyrite changes during grinding. This knowledge is critical for devising control strategies to optimise grinding and flotation operations in mineral processing plants.

Automated summary

The study investigates the impact of different grinding conditions on the surface chemistry evolution of pyrite during the grinding process. It is found that grinding with forged steel media leads to low surface hydrophobicity, while grinding with high chrome steel media under nitrogen gas atmosphere increases the natural hydrophobicity of pyrite by reducing the reaction rate of fresh surfaces. This understanding is crucial for optimizing grinding and flotation operations in mineral processing plants.