Dielectrophoretic Behavior of Clay Minerals I. Dielectrophoretic Separation of Clay Mixtures

Abstract This paper describes a method and apparatus for separating clay particles according to their ability to store electrical energy. Separation is accomplished by opposing an electrical dielectrophoretic force by a mechanical centrifugal force. The apparatus used to create these forces consists of an axially rotating, fluid-filled cylinder in which a non-uniform electric field is maintained by means of radially disposed electrode vanes. The behavior in this separator of illite, prochlorite, montmorillonite, halloysite, and kaolinite is reported. Observed differences in the dielectrophoretic force acting on these clays indicate that they can be separated one from another by this method. The basic equations which govern the motion of particles in this separator are discussed. From these equations and known electrical properties of clays it is concluded that the large dielectrophoretic force which acts on a clay particle must have its primary origin in an interaction between the non-uniform electric field and induced ionic space-charge which presumably is created in the particle’s interlayer regions and in the loosely associated external surface layer.