The isomotive cell, a new particle separator using dielectric polarization

Summary form only given. The behavior of particles in a combined gravitational and nonuniform electric field is used to produce separations of materials having different dielectric constants. This paper describes recent improvements to the apparatus previously used for the continuous separations of physical mixtures. The separatory operation consists of passing the finely divided material through a pair of diverging electrodes while the particles fall down a tilted tray. The apparatus is in effect an electrical siphon, and requires extremely little electrical energy other than that to produce mechanical vibratory motion and falling of the particles through the cell. In this phase of the work, studies were made of the electrode design required to produce best separation. In particular it was shown that a specific electrode design is required to minimize clumping due to dielectrophoretic forces while the particles are passing through the cell. The improved cell operates in a small tank of dielectric liquid, and possesses electrodes of improved design, having high curvature and small spacings. It is capable of making separations on materials of even very low dielectric constant, such as those containing quartz. The ability of the isomotive cell to produce separations on materials of closely similar dielectric constant was demonstrated on the system A120 - CaF2 having dielectric constants of 8.5 and 6.9 respectively. In a further test of the isomotive cell, samples of swarf, which are diamond wheel cuttings obtained in certain manufacturing operations were subjected to the action of the nonuniform electric field. This material was mostly alumina containing a small quantity of industrial diamond (about 0.2%) in the size range of 5 microns diameter and over. The low exit of the isomotive cell was observed to be passing material in which the diamond concentration was enriched by a factor of 25.