The thin-layer wicking technique was employed to determine the contact angles (q) of different liquids on powdered talc samples. The measured contact angles were then used to calculate the surface free energy (g_S) of a talc sample, including its dispersion (g_S^d), acidic (g_S⁺), basic (g_S^-), and acid-base (g_S^AB) free energy components, using the van Oss-Chaudhury-Good (OCG) equation. By conducting the measurements at two different particle sizes, it was also possible to determine the free energies of the edge and basal surfaces of the layer-structured mineral. The results show that the basal surfaces are basic and the edges surfaces are acidic. By determining the surface free energies before and after treating a talc sample with a polymer, it was possible to determine if the reagent adsorbs preferentially on the basal or edge surfaces of the mineral and with what possible mode of orientation. The method developed in the present work can also determine the particle size at which fracture begins to occur along the edge surfaces of the mineral.

*Corresponding author: Tel. (540)231-7056; e-mail: ryoon@vt.edu

1Present address: Department of Mining and Geological Engineering The University of Arizona,Tucson,Arizona 85721