Experimental insights into surface chemistry and wetting properties of mineral particles in multiphase systems

Mineral separation processes like froth flotation rely on differences in wettability, emphasizing the need to understand the interfacial properties and microscale processes occurring on material surfaces. Although the Young contact angle is the primary parameter for wettability quantification, it faces significant limitations when applied to fine particles due to their non-planar shapes and rough surfaces, making the analysis highly system-specific. This study explores the challenges related to the wettability of minerals, including carbonates, quartz, pHosphate minerals such as apatite, and rare-earth-bearing minerals like bastnaesite and monazite. Their respective wettability was determined using static and dynamic contact angle measurements, solvent extraction, and particle attachment-droplet coverage analysis. A higher tendency of apatite, monazite, and bastnaesite to attach to oil droplets under specific conditions (pH around 6) can be attributed to their greater hydrophobicity (higher contact angles >55°). This behavior likely arises from their surface chemical composition and crystalline structure, which favor lower surface energy and reduced affinity to the aqueous phase, while carbonate minerals and quartz, being more hydrophilic minerals, remained in the water phase. The analysis of mineral surface properties indicates the capability for processes like solid-stabilized emulsions to selectively separate and concentrate specific minerals.