Application of ToF-SIMS to predict contact angles of pyrite particles

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used as a technique to predict the particle contact angle of pyrite and contact angle distribution of pyrite ensembles, with size ranging from a few micrometres to a few millimetres (up to 2.36 mm). The pyrite samples were subjected to different oxidation treatments (e.g., heating, hydrogen peroxide conditioning) to obtain a range of surface chemistry. The ToF-SIMS data set is examined using a multivariate statistical tool, principal component analysis (PCA), to find patterns in the data and to identify the surface species contributing the most to surface chemistry of pyrite samples. Surface chemistry variation of the pyrite samples (via ToF-SIMS signals) are correlated with the measured Washburn contact angles. A ToF-SIMS-Contact Angle model of only two ToF-SIMS ion peaks, FeOOH+ and SO3-, is derived, which is used to predict contact angles of pyrite surfaces. Using this model, the contact angle variation across a single pyrite particle's surface and the contact angle distribution within pyrite particle samples are determined. The ToF-SIMS-Contact Angle model also allows the prediction of contact angles for coarse pyrite particles (- 2360 + 600 mu m), which cannot be easily determined by traditional methods for particulate samples, e.g., the Washburn capillary rise method. The ability to determine the contact angle distribution of particles by ToF-SIMS is very suitable for mineral flotation studies, particularly for studying the relationship between comminution and flotation behaviour, and for devising control strategies to improve flotation performance.