An investigation of mineral floatability versus mineral surface exposure and hydrophobicity by high-resolution X-ray microcomputed tomography, film flotation, contact angles, and modeling

Abstract

Determination of mineral floatability versus mineral surface exposure and hydrophobicity has been challenging because of significant deviations of flotation model assumptions for real mineral surfaces and the unavailability of suitable research tools. Here, we report a successful application of combined advanced experimental techniques and modeling to determine mineral floatability versus mineral surface exposure and hydrophobicity. Specifically, high-resolution X-ray microcomputed tomography (HRXMT) was used to determine the surface exposure of composite mineral particles of quartz and chalcopyrite and compared it with the mineral floatability obtained by film flotation experiments and the contact angle (CA) of the mineral particles. The surface exposure was obtained from the HRXMT images using in-house software. Cassie's theory was applied to estimate the CA of composite particles from the CAs on single mineral phases. The mineral floatability was described by extending the new theory on max adhesion force (tenacity) that holds the particles attached to the bubble surface. The comparison shows a good agreement between the tenacity, surface tension, and the CA calculated from the surface exposure data together with the CA on single mineral phases. This is the first work that quantifies the effect of surface exposure on the floatability of composite particles and can be applied to predict the flotation performance of the composite particles in the mineral processing industry.