Contact angles measured at mineral surfaces covered with adsorbed collector layers

Improvements in the measurement of contact angles at heterogeneous surfaces and their interpretation were applied to mineral flotation systems where a hydrophilic solid surface is covered by a hydrophobic collector and forms a heterogeneous pattern. The examination of the contact-angle hysteresis an d the contact-angle vs. drop-size relationship for the fluorite-carboxylate and apatite-carboxylate systems supports the model of nonuniform formation of adsorbed layers through nucleation and growth of hemimicelles at the mi neral surface.