High-voltage monitoring in electrostatic separators

High voltage is known to be one of the main control variables of any electrostatic separation process. From this perspective, the aim of the present work is double: develop an effective high-voltage monitoring system, and demonstrate that it can be an useful tool for supervising the overall operating conditions of electrostatic separators. A custom-designed virtual instrument was employed for processing the experimental data provided by a high-voltage probe the output of which was connected to an electrometer. In several experiments, the output of the high-voltage probe was also connected to a digital oscilloscope, in order to obtain a better characterisation of the variation of the electrode potential after a spark discharge. The laps of time without corona discharge and/or with low electric field intensities could thus be rather accurately determined, and the impact of spark discharges on the outcome of the separation process evaluated. The dispersion of high-voltage measured values was found to increase in the presence of the material. The statistical analysis of the data revealed a significant correlation between the standard deviation of the high-voltage and the concentration of metal in the processed material. These findings could be helpful for the optimisation of the operating conditions of the electrostatic separation applications where the metal content in the feed materials is characterized by important fluctuations with time.