Capability evaluation and statistic control of electrostatic separation processes

The variability of the outcome is often deplored by the users of electrostatic separation equipment. This paper is written with the aim of showing how statistical process control methods could contribute to the improvement of users´ overall satisfaction. In order to validate a procedure for evaluating the short and long term capability of the electrostatic separation process, the authors carried out a series of experiments on subgroups of chopped electric cable wastes, similar to those currently processed in the recycling industry. The first set of experimental data enabled the computation of the upper and lower limits of two types of control charts. The second set of experiments was designed to evaluate the ability of these charts to detect typical situations of abnormal operation of the electrostatic separation equipment. Several recommendations have been formulated based on authors experience as consultants for the recycling industry.