Continuous Separations of Suspensions by Nonuniform Electric Fields in Liquid Dielectrics

Suspensions of various solids in organic dielectric liquids can be separated continuously into their components by pulsating direct or alternating current electric fields of modest strength. The method and its important variables are described, together with the results observed for several systems. It is found,for example, that there exists a critical lower voltage and a critical upper voltage between which the operation must take place if appreciable separation is to take place. Best results are obtained if the dielectric constant exceeds that of the liquid. Among other separations possible, it is shown that zircon‐rutile particle mixtures readily separate under conditions of dielectrophoresis. These materials cannot be separated by density or magnetic methods. A simple theory for the forces exerted on the particles sitting in combined gravitational and nonuniform electric fields is given.