PARTICLE CHARGE NEUTRALIZATION IN ROLL-TYPE ELECTROSEPARATORS

Safe and efficient operation of industrial electrostatic separators re quire a strict control of the residual electric charge of the particle s emerging from the process. The present paper analyses the efficiency of charge neutralization accomplished by conveniently located electro des, energized from a.c. high-voltage supplies of 1250 Hz and 50 Hz. T he tests were carried out on a laboratory electrostatic separator, pro vided with two wire-type corona electrodes connected to a fully-adjust able d.c. high-voltage supply of positive polarity (0...30)kV peak val ue. A needle-type corona electrode was employed for the neutralization of the charge. The particulate material used throughout the experimen ts consisted of mm-size PVC granules, issued from chopping of electric wire insulation. With both the 1250 Hz high-voltage supply and the co nventional 50 Hz high-voltage transformer, about 80% of the material i s removed from the surface of the roll electrode, following charge neu tralization. The tests should continue with a variable frequency high- voltage supply, in order to establish an optimum value of this paramet er under various operating conditions.