Influence of material superficial moisture on insulation-metal electroseparation

The efficiency of separating by electrostatic means the constituents of a polyvinyl chloride (PVC)-metal granular mixture depends on the moisture content of the materials. Laboratory research has been carried out to determine the acceptable superficial humidity of the granules to be separated. The experimental study has been implemented on a roll-type laboratory separator with a corona electrostatic field. Ten samples of 50% PVC and 50% aluminum or copper, with a moisture content in the range W=0-0.9%, have been identically processed. Several diagrams show the influence of the humidity on PVC and metal recovery from the granular mixture. It is found that efficient PVC-metal separation can be obtained for a moisture content of less than 0.3%. Experimental results are qualitatively discussed on the basis of the electrical charge of the PVC grain, the time constant of the discharge process, and the electric image force