In this paper the selection of a suspension for the electrophoretic separation of insoluble and slightly soluble minerals is analyzed. Studies about the electrokinetic behaviour of minerals such as quarz, fluorite, scheellite and calcite, as a function of the nature of the particle-fluid interface, have been done. A group of well known reagents used in mineralurgy, such as collectors, floculants, dispersants, pH regulators and also some nonconventional reagents, like buffer solutions, were ernployed. It was observed that the reagents used in the experiments produce significant variation on the zeta potential of the minerals, effect which depends on the type and concentration of the reactant. From the analysis of the results it can be concluded that the buffer solution of NACO3/NaOH at pH 9 is an appropriate suspension media which can guarantee the separation of the minerals in continuous electrophoretic separators.