Electrostatic separation of insulating and conductive particles from granular mixes

Electrostatic separation is extensively used for the selective sorting of g ranular mixtures, by means of the electric forces which act on charged or p olarized bodies. The roll-type separator with combined corona-electrostatic field has been proved to be the most advantageous solution when the purpos e is to isolate conductive particles from non-conductive ones. The paper pr esents the contributions of the High intensity Electric Fields Laboratory o f the Technical University of Cluj-Napoca to the development of this soluti on for various industrial applications. The first chapter is devoted to the theoretical analysis of the phenomena and points out the multitude of fact ors which influence the efficiency of the separation process. A special att ention is paid to the study of the corona charging conditions of insulating particles. In the second and third cahpters, the authors show how the resu lts of numerical modeling guided the design of new equipment and the optimi zation of their operating conditions. Laboratory and pilot plant tests desc ribed in the forth chapter brought evidence of the effectiveness of the pro posed technologies. The presentation of several applications in the recycli ng industry concludes the paper.